It's critical. Right now it's one of the single most important ways they use to balance the game. Especially since we are, and we're going to be even more with rotation, in a Vmax format were for the most part they're just 2HKOing each other, having matchups were damage just doubles so they can be OHKOed is huge.
Although I understand the sentiment, that's never going to happen, the TCG is a completely different beast, and managing and balancing the exact type charts we have in the VGs would be impossible.
I would like to see weaknesses have a lesser role in balancing though, right now it's just "pick a consistent deck with good matchup spreads and hope to avoid the 20/80 ones that exist because of weaknesses". But I don't have a better solution myself for that. As much as weaknesses make the game swing-y and all-or-nothing at times, it ensures even exceptionally strong archetypes are kept in check precisely by having those "you pretty much lose by default because of weakness" matchups, wereas if it didn't exist, any archetype with exceptional qualities would just completely take over the game and make it stale and uninteresting.