This increase in criticality and negativity is, in my experience, pretty common for people who become extremely invested in something and spend a lot of time on it, and it's usually attributable to burnout. If you're hoping a new expansion will give the same level of excitement as they did when Dominion was still new to you then it's never going to happen. Once you develop a deeper understanding of the game and the implications of new mechanics it won't reach the same highs of excitement because the Aha! moments don't come as often and aren't as fundamental or profound. Maybe consider taking a break for a while?
To be more on topic, Empires has been a smash hit with my group and its my favourite expansion by a mile (have only played base, intrigue, seaside, prosoerity and empires). One of my friends, after having played his first game, went out and bought his own copy and has had a lot of plays with his family. Only card we all aren't sure about is Catapult / Rocks which we all feel is weak and not worth buying, but everything else that we first looked at and were unsure about, like Salt The Earth, have ended up being fine. We were worried Salt games would end instantly and not be interesting, but it doesn't happen. Early salting is suicide, the opportunity cost too large and the one point so easy for other people to overcome. (Edit: yes I know about Salt + Feodum, I know you were getting giddy with excitement to edge-case that sentence)
So yeah, Empires. Bloody amazing! Always wanted to see the return of VP chips and have more than 3 things use them and boy howdy Empires was more than I ever could have hoped for and wildly exceeded even my grandest expectations. Debt is amazing and just a brilliant way to introduce powerful cards that have to cost 8 without having them compete with provinces so people will actually buy them. The people in my group who normally hate attacks still enjoy the attacks in Empires, as even though Legionary is strong you have to work harder for it and feels fairer to them, and Enchantress is novel and they find it easier to play around (although we forget one is in play all the time). Finally the Landmarks add a ton of variety in a wonderful way, feeling like rule modifiers that can change your decisions in both subtle and not subtle ways. The game I had with Bandit Fort was the best game of Dominion I have ever played even if it took an hour in 2 player, learned the hard way that you usually still want the silver.
Empires delivered everything I wanted from Dominion in a way that surpassed anything I could have hoped for, thank you Donald!