The thing is though, the tone and feel of the old games and Awakening/the "my castle" stuff in Fates is completely different from each other. (The Nohr version is intentionally trying to be more familiar in tone and feel to the old games) This change in tone and appealing to a wider audience has left many of the older fans feeling betrayed, especially since Fates has basically confirmed that this is the future of the series. The old fans feel like they have been left to rot, while Intelligent Systems (The company that makes the Fire Emblem games, IS for short) chases new money. While IS has been trying to appeal to both the old fans and the new with Fates, the problem lies in that many of the older fans absolutely loathe many of the things that Awakening (and "my castle", which includes marriage, children, and a customizable main character) brought to the table (which largely appeal to the new fans), and are in outrage about them even being included in Fire Emblem Fates, as to them, these features take away from the Fire Emblem feel, and in their eyes turn the game into "Otaku pandering garbage." (NOT my thoughts or feelings on the matter, but that's been a very common statement on the Fire Emblem subreddit, for example) These changes are more drastic than those between Pokemon generations, and while I do think many of the people are overreacting, I can understand why. They feel that their favorite series is now being made to appeal to a completely different audience. (The only Fire Emblem community I've seen be civil about these new things is Serenes Forest)
Time travel is simply a very risky move, and can completely undermine a narrative if done poorly. Children were in the last game, and unless it's a time skip people don't want time travel in another game, especially if they are plot relevant.
It's a bit irritating to me though, that a lot people are ignoring the advertised improvements that Fate is bringing to the table. It brought some desperately needed balance to certain mechanics such as pair-up (which was introduced in Awakening and was problematic because in the hands of a skilled player in completely broke the game), and 1-2 range weapons. (they are now unable to double attack, which is good as they have been breaking the games since the beginning of the series)
Apologies for a long winded post, especially if I did a poor job making sense. (It's very late where I'm at, and I'm tired but I don't feel like sleeping.)