I'm an unabashed Eurogamer, and really like digging deeply into heavy Euros, but they have some problems:
1) High barrier to entry related to difficult mechanics, iconography, decision making
2) Long playtime
3) Groupthink tendencies to develop with repeated plays with the same gaming group
4) Realization that at higher levels, especially in 2P, "cutthroat" tactics are usually among the most optimal ways to play
5) Lots of neat titles and limited gaming time = few plays per game before pulling out a new game
These barriers routinely make it very difficult for me to get experience with games like Caylus, Agricola, Tzolkin. Heck, I actually studied Caylus extensively including reading the rules, printed out a pdf of all the buildings, read all the strategy articles on BGG, and then still had to fight a tough learing curve on BSW to get any plays at all. I simply CANNOT get that game to the table IRL and have 100% of the time had to omit the provost or everyone just quits.
My wife loves Race for the Galaxy and we both climbed the learning curve together and have very good competition together. Unfortunately, we've been experimenting with the Orb Scenario from Alien Artifacts, and I'm convinced that a strong blocking/denial strategy is the way to go at least in 2PA. Needless to say, this hasn't led to a very pleasant gaming experience.
I think this is why a strong online server is the only way to fully mine the depths of these games. With Dominion, I'm fairly certain I never would have gotten past the Big Money stage if it weren't for online Dominion and these forums. However, Dominion has a low enough entry point that I can get it to the table routinely. The more it at least gets to the table, the more people actually have a chance to enjoy it.
The real question to me is: Why is a game like Hearthstone more popular than Dominion? Having played both, I conclude that Dominion is a flat-out better game. Whatever Blizzard is doing, we need to help RGG and MF do!