Yeah, I know. I find it quite sad the direction Pokémon isn’t going in. And outside of Japan isn’t doing any better. In Lost Thunder, 16 out of 214 (excluding SRs) were Lightning types. And 36 were grass types. In a set called Lost Thunder. But honestly, themes sets shouldn’t be the biggest of the players concern. I think the most important problem is artificial set bloating, and with my budget, I might have to stop playing because of all the giant sets with so many fillers. Does anyone remember when opening packs was fun?
I think as a collector, themes in a set can actually be very important to the collectible appeal of a set if done right, granted that they're being attempted. Certain sets can be more broad, like, say, Base or Expedition, and of course those sets have their own appeal. Artwork, value, there's MANY factors into wanting to complete a set.
That being said, in this case, talking about themes: If a set has a certain motif to it, that can be an appeal on its own. Southern Islands is a great example of this I think where the entire miniset has collectible appeal as one big scene. Furious Fists has the appeal of the fighting motif through almost every card, and a lot of artwork linking together a large scenario of a big fighting tournament. Even small instances where cards tell a story have that thematic appeal to it, many cards in Legendary Treasures has that appeal in a small scale throughout many of the cards. Take Plasma too, for instance. Team Plasma fans will be drawn to that set's appeal because it has that appeal of lots and lots of love for Team Plasma. It was so well done back in those days, and it's a shame whoever is behind the TCG nowadays doesn't understand that.
Artificial set bloating is another HUGE issue, I have to agree-and anyone who knows me around here may have seen my opinions on that, so I'm not going to go into that hour long tangent again. I've made it so I'm just not going to deal with Gold Items and Hypers. If you want to work with your budget, I strongly suggest you go for the singles market. It's been incredibly friendly to my budget and it's in fact exponentially boosted my collection. I'm not sure if you're a collector or a player, but I suggest either way to look towards that. Packs with sets like these aren't going to get you much anywhere.
That being said, I miss packs a lot. Even BW with it's terrible pull rates was still a fun era. I think opening packs can be a little fun nowadays, but the peak of it in this era was definitely Shining Legends. That set was actually worth opening for a while, with amazing products and a set that was easy enough and fun to complete. I don't open boxes anymore. I haven't opened one since my garbage Sun and Moon base box. Because it just isn't the same as XY and BW was, but again, that's another thing I've gone into before. TL;DR, it's just not as fun or rewarding to open Sun and Moon boxes as it is compared to XY or prior.