Seems like to this point, everyone in this thread had positive memories of the "old days". I'm not here to bash because I definitely remember a lot of the positives, but I'll also point out some of the negatives.
Biggest difference is that there were a lot more people around then. Now, some shards are still pretty busy today, but even the busier shards are nothing like they were at that time. This is both good and bad. I do have positive memories of having dozens of people to talk with around Brit Bank, of getting armor repaired at the forge, and a lot of other things that were really great. But I also remember huge arguments & fights over petty things because there were so few options & places to hunt and adventure. Having high population density definitely has its pluses and minuses; some people love to live in Manhattan, other people would rather die before living there.
Whoever said people dressed uniquely...are you on drugs

Actually, I'm not here to bash anyone else's memories, but what I recall was that everyone ran around dressing & looking exactly the same (or at least aspired to look the same). Guys ran around in kilts & blessed black sandals (can't say I miss that) or in suits of basic armor types; and girls all had long hair dyed white. Of course, there were a lot fewer options available. Basically you had a normal dye tub and maybe a black dye tub. You didn't have different colored cloth, clothing from the various expansions, a big variety of mounts, etc. Again, just what I remember. These days, there's definitely a lot more variety available, although I'm definitely on the bandwagon that something needs to be done so everyone doesn't have to walk around in floor length robes.
There were far fewer viable templates to play. These days, one of my favorite things is to figure out if some skills can work together to create a more effective (or more fun) template to play. Sure, PvP may be dominated by a few specific templates, but that's always going to be the case as people try to squeeze out an edge. But if hard-core PvP isn't your top priority, you've got a lot more options these days; and the opportunity to go to 120 in a skill, or stop at 100, or even 80 lends flexibility. Used to be, every warrior carried a katana or Kryss; there simply weren't very many options.
Now, I will agree that standardized templates & gear made PvP "back in the day" more of a skill based affair with one HUGE caveat. It was skill based if people had equal connections. These days, gear can be a big imbalance, but during the entire period of time leading up to AoS, a lot of people (I will speculate that a majority of people) were on dial-up. Combine that with much higher population density (anyone at the pac rares festival knows that big crowds still spell lag, even today with great connections) and you can picture what happened.
A lot of people, like myself, went around on foot because lag gave no benefit for being on horseback. Now picture what PvP was like for me with someone zooming around on cable internet on a horse. Yeah. So, I really don't agree that PvP was skill based to a larger degree back then. Sure, if you fought someone who had an equal connection, it was likely neither side would have a gear advantage; but there was an inherent advantage that could not be overcome in many if not most PvP battles - the side on dial-up had zero chance of winning.
So, I'll just say I do have very fond memories of my early days in UO. Mostly, I remember the great friends I had in the game. I remember the sense of wonder when I would go around discovering the world and see so many people doing their thing everywhere. But I also remember squabbles related to overcrowding and much more limited opportunities for things to do. I think PvP would benefit from a return to "classic" rules & gear; but every other aspect of the game I can think of would suffer. For someone like myself, who enjoys PvP, but also champ spawns, the ML lands, the opportunity to build around new gear, and all the new stuff in SA, I think it would really be a step back. In my opinion, a classic shard & ruleset addresses one specific set of needs without really thinking of how all the various people enjoy the game.