Multiple Map Objectives I would like to see more of. Such as survive for a set number of turns or don't let thing fall, or protect thing. Instead of rout the enemy every chapter.
The problem with Fire Emblem map objectives is that they're still essentially rout maps. I cannot think of a single Fire Emblem defend map that you're better off defending rather than just routing or killing the boss.
Playing some of the games in the series again, there isn't anything inherently wrong with rout maps. Its just that the map and scenario has to be interesting rather than endless floods of units bum rushing you from forts.