I can understand the complaints about FE Fates, as someone who's only played Radiant Dawn and Awakening so far.
They went a bit far with the fanservice. It is an optional feature, so I guess I can't complain that much.
I don't like it how the newer fans like the series for the waifu stuff rather than for its core as a strategy RPG. But those features make the games sell, so it's easy to see why IntSys is putting all that stuff. It's profitable, it helps the series sell. In the end, it's business.
All in all, Fire Emblem as it was before Awakening isn't likely to be a thing ever again, unless the waifu things drop in popularity.
Personally, I'm not too fond of the new direction the series is taking with all the pandering to certain kinds of fans, but hey, the essence of the series is still there.
Between the series being dead (had Awakening not been successful) and being alive but with the unnecessary pandering, I prefer the latter.
I don't like that kind of stuff, but if it's optional, it's not like I need to use those features in the first place, so I really can't complain.