What I'm understanding from this is that OP feels that the difficulty of Coil is a little high and wants an easier mode. This easier mode will be renamed Normal Mode, while our current level of Coil will be Hard and Savage Extreme or... something. I would like to point out that the current mode is, indeed, Normal Mode. The thing I see from all this is really that you, dear OP, simply feel that the bar is a little too high for what you consider "Normal", which is, a matter of perception.

EG: I feel that playing Guilty Gear on anything other than Maniac is easy, my friend feels that playing anything other than Lunatic on Touhou is normal. While I feel that playing Touhou on anything other than Normal is pretty damn hard and he feels that playing Guilty Gear on anything other than Normal is nuts, it doesn't change our perception towards the individual games. This is because we've gotten to heights where our perceptions towards "Normal" and the bar is a little different from that of many others. Note, this is okay, because difficulty is really a matter of perception in this case.

I recently did t5 in a learning group with i90+i100 gear. We didn't clear it. I was nervous as hell before going through it mind you, but when I did I actually laughed. Oh god, the whole thing was so laughably easy. Sure, we wiped at Snakes, but people blew snakes up early and I didn't have enough heals thrown on me to survive four snakes. That and DPS were getting tired at that point I believe. Also, some silly mistakes from puggers, but it was otherwise all around... easy. Have I gone to t6? Nope. Do I think it will also be as laughably easy once I figure the whole thing out? Yes.

So what's wrong? Is the bar elevated too high for people to actually challenge?

Pfft. Hardly. I would say that the gaming level of the community is terribly low ((HoTs before pulls/spawns + over heals, tanks who don't use CDs or AoEs, DPS who don't use their buffs or disengage as required, players who would rather ignore game mechanics because it's so much easier to burn a boss you can't burn for example)) and the idea of lowering the bar is hilarious.

For the healer who points out that he can do things perfectly but mess up because of a pug, I'm sorry for your terrible experiences. That doesn't make a good reason for lowering the difficulty of Coil though. Players needing to "git gud" is never a good reason for content nerf.

I feel that the bar set for the content is just right. Players just need to step up to the challenge.

Before we go to the "WoW examples, WoW standards!" I would like to point out that WoW has been made easy over the last few years. I didn't really play WotLK, but from what I've been told from the Ye-Olde-Raiders-From-Yonder-Days it's laughably easy compared to the old days of raiding and the like, especially with add-ons. Also, I would like to point out that the use of add-ons and the like have, in my humble opinion, dulled the killing edge sense that gamers developed. Your idea of "stare at the HP/cast bar" is rather off. People who didn't have the wonderful little tool we now know as add-ons simply looked towards the cast/HP bar, took an overall look at their cooldowns, positions and made a quick decision in what would amount to less-than-one-whole-standard-GCD in this game. The closest thing to a add-on notification was that instinctual gut feeling telling you "Disengage soon".

And that's "Medium-Core".