It does matter for decentralization. The higher the block sizes, the more centralized a network is, because storage isn't exactly cheap - this is the whole reason for the block wars that happened in 2017. I very much think that we should cap that shit because it's simply wasting storage space on useless trash, and I don't like that at all. The only way for the network to be sustainable, in my opinion, is to cap the amount of data you can cram in (maybe take the NYT headline that Satoshi used and set the max to that, as a symbolic message and limit).
I do agree that LN is where the focus is right now (rightfully so), but ignoring the problems that come with what is being done to the network right now is not a smart idea. LN is nothing without the solid foundation that is the base Bitcoin, and that foundation is under attack (not an immediately strong or super concerning attack, but an attack nonetheless)