We used to only have one DPS that could resurrect and that was Summoner. At the time this was the case, Summoner was a lot harder to play (or at least, easier to mess up because some people barely did any damage on it) and was limited to 1 rez per minute. So, often your party would only have healers to rez, and if you wanted to survive, keeping the healers (or occasionally a SMN) alive was crucial - even at the cost of something like Clemency. I liked this because of the pressure being on the healers or on the party to help a healer survive.

Stormblood added red mages with a virtually unlimited rez, and in so doing changed the game. Being new, everyone played RDM. And to this day, if you want to carry a party, RDM is common choice to constantly rez them all. And with SMN being so easy to play now, that is a choice as well (if expecting to rez a bit less).

Should we go back? Honestly, no point. RDM has its place now. If you want to carry a party you go RDM. It's an option. You make this judgement based on your party and if you think that what you can bring to the party most is to "carry" them with rezzes because you can do the mechs. And it does work in many fights, especially extremes. And it works for the playerbase we have, let's be honest. Often you join a party and know they're all gonna wipe because they make comments like "I'm so bad at this fight". In a perfect world, maybe everyone would be amazing and not need this but that's not the sort of playerbase we have.

And the time you don't go RDM is if you don't need/want to. If you've got a great team that won't die or the fight is so easy they can't possibly wipe that much.

There is a benefit to doing a deathless run, which really, is everyone feeling good about their clear and not having contributed less damage. So it works out.

As for the damage being scaled on it due to it having raise, really that is just SE's damage balancing decisions and they could just change those, rather than adjusting rez. But it doesn't really matter as long as the difference isn't actually big enough that you prevent parties clearing due to your damage versus other jobs.