Lazy and inconsiderate is the best way to describe a healer without swift cast. Garuda EX, deaths happen (lolmelee), Ifrit EX, Ultima HM, these are all fights where it's easy for someone to blink and be dead but it's very possible to raise and carry on np. Turning up without swift cast is like turning up in a bikini. You're short changing the rest of the group and making them pull weight that should be yours. Of course it's doable but it makes it harder and more time consuming than it needs to be, especially whilst learning the encounter in the first place.

I wouldn't even worry about dungeon grinding unless you can tag along with a tank for instant queues, just got AE some fates down, it's an evening or two's effort tops.