I played them in order, so I could get how someone wouldn't enjoy 1 as much as the others if it wasn't how they were introduced to the franchise. Being dropped into such a well-done cinematic game was a game changer at the time.
3 is easily the worst, IMO, though. I can accept jumbling around 1, 2, and 4 in rankings to an extent (although most agree 2 is the best), but I don't see much in 3 that makes it worth ranking above the rest.
As someone who rarely touches his PS4, I'm okay with franchises that wrap up in a timely fashion. Bad or unnecessary sequels irk me. Among Naughty Dog games, I enjoyed The Last of Us even more than any Uncharted, and even that I don't really want TLOU2 to be a thing (because the original was such a well done package that I don't feel it needed a sequel).
I think 2 is clearly a step above the rest. 1 was kind of plain for me and there wasn't really any locations that I can remember (it all took place on a island right?), 3 was just a step down from 2 and didn't really improve anything and 4 went way too far with the swinging which way very simple and not very hard.
I enjoy a good sequel or prequel especially when there aren't really any games like Uncharted, except Tomb Raider which I haven't enjoyed nearly as much.
If Mario, Zelda, GTA, etc. can keep going and changing for 30+ years I don't see why other games can't change... Even 4 and Lost Legacy changed up the Uncharted formula a bit and became less linear and more open.