Well... on one hand, I get what you mean. If it technically should be lying in a heap and bleeding out and twitch a little, it seems a bit weird. But on the other hand, I see it as that stage being when you get it down to 0 hp. When it's /almost/ dead, that's when the adrenaline rush hits, together with the desperate "Hell no, I'm not gonna die before they do!" where it throws out those really risky suicide attacks cos it has no other choice -- if it doesn't use those "common side effects include death or long-term invalidity" attacks, it's gonna die anyway. ;p
There was a parody on the classic fantasy novel format that I read once. Basically brought in all the cliches and told the story through basically the trope names/descriptions. Don't remember exactly how it went, but ends with something like the Nameless Hero going 39 rounds with the Evil Overlord, but of course the Evil Overlord cheats and hides metal junk in his boxing gloves. Then in the last round, the Nameless Hero's down for the count, when the Princess blows him a kiss, someone gives him an overdose of holy water, and the Cryptic Old Man tells him a final secret. Just before the count is up, the Nameless Hero gets to his feet, dusts himself off and goes, "Dude, you forgot to tie your shoelaces." And when the Evil Overlord looks, the Nameless Hero knocks him out and wins the fight. (And for some reason, this does not count as cheating.)
That was a total side-note, but the point of it was that the same thing happens to heroes in most novels/anime, as well as some games, and ever since I read that parody, I've referred to it as the hero getting an overdose of holy water xD
To return to the topic of phase skipping in raids (and primals and other stuff), I actually like it that they've made some fights impossible if the wrong phase is skipped or if too many phases get skipped. Say Ifrit, for example -- get his HP too low too quickly, and he'll place his nails and then jump just a few seconds later before you've even had a chance to take the nails out. Or like Canadane said about 1.x Garuda, with holding back and rushing dps (which is so much easier now when they've enabled us to see actual percentage of mob hp). Sure, when you're at that point, the raid/primal is already a cakewalk, but it also adds a different difficulty to it, with knowing when to hold back and not.
I'm definitely not a progression raid player -- started way too late due to gathering up a like-minded static, and while we did our best to catch up, we unlocked FCoB mere days after they added Echo =/ It'd have been fun to try it before that. But despite that, and despite my previous paragraph, I don't agree that wanting to skip phases means wanting to skip the entire fight and just getting the loot. It's a bit like saying, "Well, my goal is to ace all the tests, so why not just skip all the tests and just give me the damn diploma already." It might be part of the goal to get so good (or geared) that you'll skip the phases that otherwise might trip you up, but that's not the entire goal. It's more like... the proof of you having gotten that good.
Yes, I'm aware it's not the best analogy, and that the counter-argument would be more like "My goal is to ace all tests, and I'll cheat if I have to, so since we know I'm going to ace them, just gimme the diploma." And you could see getting to the phase-skipping via overgearing as cheating. But most progression raiders don't need the gear to beat it, so by the time they're overgearing it, they're just in it for loot or fun (depending on the fight/raid) and not to beat it. And for non-progression raiders... I'm totally generalizing here, but mostly we're not progression raiders due to lacking either skill or interest, so... I see overgearing a little bit more like someone with a disability (say dyslexia) getting the aids needed to get to the same 'level' as others (getting oral examinations instead of text-based, for example).
Err... I'm going to stop here, and I'm sure there are plenty of holes in my reasoning ^^; C'alogic doesn't always make sense to others.