Engage has no real replay value and all it has for gameplay is a little bit more quality of life, FE gameplay has never been anything worth praising. No NG+ was a stupid decision in conjunction with the decision to de-emphasize grinding. Except the game has plenty of things you'd want to grind for so it just stands out as an exceptionally stupid decision.
It gets brushed aside because the writing is generally unimpactful garbage even if it never does reach the lows of either of Dimitri's routes in Houses or Hopes. It does have a few of it's moments in the story and the supports are generally good but the supports are a pain to grind for because the game is badly designed around grinding in the first place and the story never comes close to hitting the highs that Houses or Hopes did either.
Engage fans just have sour grapes because the game had no impact. All it has over Houses is being a colourful game, not having AM/AG tier writing and doing better with getting the right VAs for the characters. The same people going "It'S bEeN fOuR yEaRs!" would have a heart attack if they saw people talking about any other older media they enjoyed but that's only if they weren't being intentionally dishonest.
Prime 4 isn't being made by the dudes that **** out three of the worst Castlevania games and has way more expectations surrounding it.