There is rule complexity. Cards like Possession and Patron suck in this respect.
There is card complexity. Something like a Traveller line, a split pile or a card which does several things like Scrying Pool can be considered as relatively complex in this regard. Just take the amount of text on a card as rough benchmark for it. I love this form of complexity and am probably in the minority.
I think that fan cards should be more complex than official cards as they can and should combine stuff from expansions. For example Night cards and Coffers/Villagers are just a natural match.
There is emergent complexity. It is kinda like with chess, you have a bunch of simple movement rules yet a complex game with immeasurable depth emerges out of it. In Domnion you have simple cards that, in combination, lead to something sublime. I think we all agree that we love this aspect of the game. Cards which increase emergent complexity are often cards with high combo potential.
What I am against is a card that has high rule complexity (or ambiguity) yet low card complexity as the former is only justified by the latter.
It is a akin to playing a heavy Euro that has not been "trimmed" well. If you do complex, keep it as simple as possible understanding-wise.
When Nocturne was the hypercomplex mess that it was, I offered my help. I tried to steer him towards simpler designs before, with Adventures and Empires. What it got me was being considered to be antagonizing him, and lots of folks jumping at his defense without thinking twice. I have no interest being in that spot again.
So no, I won't ask him.
As I love expansions with high card complexity like Adventures (engines!) and Empires (alternative ways to green!) I am on the opposite side of the spectrum (although I would argue that your Events, Seasons and Spellcaster cards as well as the new Fame concept are not necessarily on the hypersimple side of the spectrum).
But I personally like my games auteur style and don't think that fans can or should try to influence designers (too much). Renaissance might be too simple for my taste but it is DXV's baby and there has to be something for all tastes. As long as something isn't bad, broken (I like Dark Ages but it seems to be the least/worst tested expansion) or counterintuitive like Patron I am ultimately fine with it.
It is interesting that you mention Nocturne. I think this expansion is an example of a lot of new stuff that doesn't really lead to something new. Stuff like Events, Travellers and Landmarks really widened the game whereas all the Nocturne stuff didn't. I don't know, perhaps it is the random nature of the Boons/Hexes that make the game more random, perhaps it is the Heirlooms speeding the game up to much which leads to more money Kingdoms. No idea. All I know is that despite the numerous new mechanics there wasn't anything as innovative / game-shattering as in the previous two expansions.
If I use my stupid categories I could say that there is more extra rule complexity that doesn lead to more emergent complexity (like e.g. Landmarks totally changing how you evaluate greening).