I never disliked it, but I can see why people react the way they did.
Disclaimer: I just started back playing civ v. I only have about 70 hours in it, and I still don't know what I'm doing.
When I look at civ Vi, despite it's cartoonish aesthetic, it seems MUCH more understandable. Being able to glance at it and decipher information quickly goes a long way.
I consider the aesthetic to be something that is comparable to tf2. (Which is also a game people complained about the art style when it was first revealed, and people still play that game, and it is still getting support from valve.)
In tf2 you can look at any class and immediately know what you are looking at, there is no way you can confuse the sniper with the heavy, or any other class.
I was playing civ v earlier today and noticed how everything blends together in a bad way. Like jungles and forests. If you don't know what you're doing and are a complete noob like me, those things can easily blend in together. And really, it's not just forest tiles, it's everything. Even after 70 hours or so, I still have to mouse over things to understand what I'm actually looking at.
With civ VI the art style makes everything more pronounced, and it makes each asset seperate and apparent at a quick glance.
This isn't to say the game will be targeted towards noobs like me, but I think it's something that everyone will appreciate when they get their hands on it. The art style has nothing to do with the game itself.
And let's be real, I bet a lot of the people complaining play the game in the strategic view anyways.
This art style makes everything so much easier to read, that you might not even need strategic view.
I imagine 5 years down the line people will be saying "Hey this game still looks pretty good as old as it is!" And a lot of that will be because of its aesthetic.