Nautilus buffs?

So, nautilus is getting a huge utility buff on his r, if you haven't read the notes already. I'm just wondering why, honestly. I've never felt that he was weak, and no one I've asked about it has felt that he was weak in any way, so I figured he must be garbage in high elo or something.

However, when I looked up his winrates and such at plat+ ranked... they were solid. between 49 and 50% on all his positions. Experienced nautilus players even reached up to 53-55% winrates on each position. This shows that once you get a solid handle on his playstyle, he's a good pick that can impact games.

He clearly isn't a godtier pick right now, but he's a solid one that works with pretty much all team comps. Why give him a buff that's going to make him even more of a monster in teamfights? I really don't understand. Can anyone perhaps explain it to me? Am I missing something?