I don't necessarily equate instancing with a lack of content, as far as size goes - Vanilla WoW had some very large dungeons for example. I think EQ2 did as well, at least early on. But I also remember hearing people bitch and moan about how long it could take to get through a dungeon, so I guess seeing shorter instances (especially the multiple wing model) isn't surprising.
I feel both instanced and uninstanced content has their own specific issues. With uninstanced content there never seems to be enough content and it tends to bottleneck. So with zones like LGuk, I think the lion's share of complaints was when you had tons of people fighting over the same loot and camps. Offer more alternatives (loot/camps/dungeons) and that would probably alleviate many of the issues, which were in part what led to instancing in the first place. With instances, if you offer enough that are decently sized and intricate then that too addresses much of the issue (I can't remember many people complaining that BRD, LBRS/UBRS/Scholo/Strat were necessarily "too small").
People will of course have their own preferences, but imho both instanced and uninstanced content suffer from the same thing. Whether people want to believe that it's simply laziness on the part of developers, or acknowledge that there must be a content creation/time+money problem since just about every MMO has an issue with this, I don't really care, but Devs have been saying since EQ1 that keeping ahead of gamers on content is almost impossible, and all we see is how different Devs and studios approach the same problem.