That's true--I forgot that DVDs can contain extras targeted towards kids. I know my copy of WALL•E has a lot of them.
There is still a logical explanation to it though: The Japanese studios require Nintendo and TCPi to do certain things. One common thing they do (Japanese animation studios in general, not just Shogakukan, TV Tokyo, and Jr Kikachu) is to require the American distributor to release the movie in theaters. In Japan, anime movies are a big thing. They frequently top box office weekend numbers. They don't realize it doesn't work that way in America. Evangelion: You Are (Not) Alone 1.01 was one such box office topper, and when FUNimation wanted to distribute it in America, Gainax wouldn't let them until FUNimation put it into theaters because Gainax thought that Evangelion is a cultural juggernaut in the west. (For the record, it isn't.) So to get it out of the way, FUNimation released it for one weekend in one local theater to fulfill that part of the contract, then released the DVDs. This may be why this Pokémon movie was only shown for one weekend: Contract requirements. It may be that the western side of Pokémon-related operations believes Pokémon can't turn a profit in theaters and thus only planned for a single weekend. Or it may be a test weekend to see if it's a good idea to release subsequent Pokémon movies in theaters. After Mewtwo Strikes Back, Pokémon movies had received sharp diminishing returns to where Spell of the Unown broke even in theaters and 4Ever lost money.
These contracts apply to what can and cannot be placed on home video. I don't see these little DVD minigames and such being popular anywhere in Japan, where portable electronics are everywhere, and another common rule is that foreign distributors cannot create their own artwork--they are given a set of illustrations of characters, logos, backgrounds, and miscellaneous items and are allowed to only use those. FUNimation runs into this a lot too: Look at their DVD sets of One Piece and notice how utterly BORING they are. This is because for each DVD set, Toei sends FUNimation a small batch of drawings (including backgrounds), and FUNimation is permitted to only use those. They can't even use screenshots that aren't part of Toei's batch. The reason for this is to prevent foreign distributors from overshadowing Japanese video releases. Japanese DVDs and Blu-Rays cost a lot more than American and European ones. They cost so much more that it's cheaper to just import them from a western country into Japan. (There is a reason for this; I can explain why later.) Enough people in Japan, including kids, understand English that it's worth the trouble. So what the Japanese studios do is ensure that the American and European home video releases are worse than the Japanese ones, so they can claim that the Japanese DVDs and Blu-Rays are more expensive, but they're of top quality. Another possible reason on the lack of extras is cost-effectiveness. This one's simple: How much will it cost to make an extra, and how many more sales will that extra produce if it was included? Over time, the western distributors may have observed that there's no noticeable effect these extras cost, so they choose not to waste money on them if the demographic who buys these extras is that small. Or the extras cause the DVDs to go up in price beyond what they believe customers are willing to pay. In this case, they're parents. I can say from personal experience working with parents that they will most likely go for whatever is cheap but new and recognizable. (This is why Sonic the Hedgehog always sells so well.) So Nintendo and TCPi cut all the costs they can to make a cheap DVD that parents would pick up.
There is still a logical explanation to it though: The Japanese studios require Nintendo and TCPi to do certain things. One common thing they do (Japanese animation studios in general, not just Shogakukan, TV Tokyo, and Jr Kikachu) is to require the American distributor to release the movie in theaters. In Japan, anime movies are a big thing. They frequently top box office weekend numbers. They don't realize it doesn't work that way in America. Evangelion: You Are (Not) Alone 1.01 was one such box office topper, and when FUNimation wanted to distribute it in America, Gainax wouldn't let them until FUNimation put it into theaters because Gainax thought that Evangelion is a cultural juggernaut in the west. (For the record, it isn't.) So to get it out of the way, FUNimation released it for one weekend in one local theater to fulfill that part of the contract, then released the DVDs. This may be why this Pokémon movie was only shown for one weekend: Contract requirements. It may be that the western side of Pokémon-related operations believes Pokémon can't turn a profit in theaters and thus only planned for a single weekend. Or it may be a test weekend to see if it's a good idea to release subsequent Pokémon movies in theaters. After Mewtwo Strikes Back, Pokémon movies had received sharp diminishing returns to where Spell of the Unown broke even in theaters and 4Ever lost money.
These contracts apply to what can and cannot be placed on home video. I don't see these little DVD minigames and such being popular anywhere in Japan, where portable electronics are everywhere, and another common rule is that foreign distributors cannot create their own artwork--they are given a set of illustrations of characters, logos, backgrounds, and miscellaneous items and are allowed to only use those. FUNimation runs into this a lot too: Look at their DVD sets of One Piece and notice how utterly BORING they are. This is because for each DVD set, Toei sends FUNimation a small batch of drawings (including backgrounds), and FUNimation is permitted to only use those. They can't even use screenshots that aren't part of Toei's batch. The reason for this is to prevent foreign distributors from overshadowing Japanese video releases. Japanese DVDs and Blu-Rays cost a lot more than American and European ones. They cost so much more that it's cheaper to just import them from a western country into Japan. (There is a reason for this; I can explain why later.) Enough people in Japan, including kids, understand English that it's worth the trouble. So what the Japanese studios do is ensure that the American and European home video releases are worse than the Japanese ones, so they can claim that the Japanese DVDs and Blu-Rays are more expensive, but they're of top quality. Another possible reason on the lack of extras is cost-effectiveness. This one's simple: How much will it cost to make an extra, and how many more sales will that extra produce if it was included? Over time, the western distributors may have observed that there's no noticeable effect these extras cost, so they choose not to waste money on them if the demographic who buys these extras is that small. Or the extras cause the DVDs to go up in price beyond what they believe customers are willing to pay. In this case, they're parents. I can say from personal experience working with parents that they will most likely go for whatever is cheap but new and recognizable. (This is why Sonic the Hedgehog always sells so well.) So Nintendo and TCPi cut all the costs they can to make a cheap DVD that parents would pick up.
