I like how the tech tree has been streamlined however it seems like it doesn't pay to concentrate solely on one tree . In the games i've played so far, there have been times when, for example, I could research heavy armor in 162 turns or in 85 turns I could get more than a few useful lower tier magic and civ techs. Maybe achieving that late game tech before other factions would still allow you to compete if you didn't grab the lower level techs, but I haven't played enough to confirm.
I don't think the way tech research works now in FE is a bad thing . Generalizing among trees early on and then choosing a path down each tree mid-late game , but not focusing on one tree in particular, is how the progression has typically unfolded for me. When comparing to WOM, it feels like I have less control over which path I choose but I imagine it is that way to keep the trees balanced.