Well firstly, there is I think the very real chance that players won't unerstand the full scope of what the ability could do for them as a feat. Second, there's no guarantee that come the final game, healer will be objectively the best feat to choose. There are likely to be other feats that could be better for other builds, or that you just like more. Players also aren't likely, in my opinion, to take the feat for every character anyway, so odds are they end up leaving the healer character behind now and then, so it's not going to come up as often as it otherwise could with every character having access to it. Basically, making it a feat turns it into an actual choice where players have to weigh up gameplay costs. With the current implementation, the only choice is whether the player finds it too annoying to use or not.
Having said that, my final point in the quote still stands; if the only reason people end up not choosing the healer feat is because they find it tedious, then the feat itself still needs to be looked at and tweaked.