I suppose if we should talk about it, let me break it down (IMO Style).
I started playing UO in 1998 with 'The Second Age'. This was an excellent expansion to the game (I watched a co-worker play from before this expansion), bringing into the game T2A. I LOVED This area and spent a ton of time here. Great way to expand the mass of the game without changing the playstyle, look and feel.
Renaissance came a few years later, bringing with it the split of Trammel and Felucca. This was not a great idea IMO, not because of the 'Non-PvP Facet' but just duplicating the landmass. If you want to make a Non-PvP facet, make a Non-PvP SHARD... don't blindly increase landmass for no reason, other then catering to one style of gameplay.
Third Dawn was a useless expansion, with a pointless 3D client that was poorly done and a waste of money, time and workload for employees. In their effort to push this PoS they made the landmass Ilshenar only accessible if you used 3D. I went there once during this expansion, and never used it again. It hurt the eyes and was just an all around PoS attempt at competing with Everquest.
Lord Blackthorn's Revenge gave us the ability to go into Ilshenar with the 2D (or normal client) and changed the way character's were created. I don't know if any of you remember the original character selection screen.
Age of Shadows changed the game forever, but they were changes I could handle. Regardless, they released this with poor decision making and in turn made the game Gear-Based vs Character-Based. PvP was crushed at this point and only the rich (or those with an abundance of time) could compete. Paladins, Necromancers, House Customization were some of the best game additions UO ever had. They kept roughly with the theme of the game and IMO House Customization was and is, without a doubt, the best thing in any MMO out on the market. Major downfall of AoS Expansion: Luna. This was one of the larger error's that UO Staff had brought into the game.
Samurai Empire was the last straw for most of the players I knew. To appease the oriental players (Japan, Korea etc) they released Ninja's and Samurai. WHAT THE F. What the HELL does that have to do with Ultima. NOT A DAMN THING. Tokuno was a waste of space. Another expansion of land that barely gets use. You get my position on this expansion, I can cuss about it all night long. I hated this expansion and believe it was the end of the game of Ultima, and the beginning of Bullshit.
Mondain's Legacy brought about Elves. This was (at the time) one of the most stupid decisions that the staff had ever made. WHY ELVES? Elves are very cliche and have nothing to do with Ultima Online. Again, WHY ELVES! There were 2 perfectly original races that UO could have chosen from with Gargoyles & Meers. Meers would have been my ideal choice, being they are original to UO.
Stygian Abyss & High Sea's I did not really get to play and was not playing during the expansion release. I had my fill of bullshit fed to me at this point and moved onto other MMO's. However I think Gargoyles were a nice addition to the game and the makeover of Ships was due.