There are two sides of difficulty I've seen vented about RM:
-Trying to complete it with a pug
-Actual difficulty running it with a premade ( and by that, I mean running with friends and fc mates and not strictly PF)
I found that the ones who voice that RM is too hard are the ones trying to pug because at its core, you're playing with people with all sorts of personal learning speeds. That's primarily what makes not just RM but any other content harder than it could usually be. Premade voices are the lowest. Some actually relished the difficulty with their premade because they know each other skills, dispositions and playing style. Even if they wipe, they tend do so less than pugs because they take time to point out observations and try different strategies and no one gets really stressed out about it.
If you find RM is highly difficult because you're trying to pug it for a clear, chances are of course you're going to intrinsically blame the trial because there's a far wider margin of errors in a collective of unknowns than known people. That's not squarely the game's problem. If you're the lone type or don't have many friends, again, tough luck: you're just going to have to put up with DF until you can find that group that has a desire to win no matter the challenges but also patient (or at least try to be) with one another.
And now my personal RM anecdote:
My first RM run took us six tries. I was co-tanking. We wiped two times on the first half but it was clear that it was just a learning process because on the third (and subsequent tries), we nailed the first part. The "difficult" part of this RM was trying to get the hang of the second half ( the part where you're transported to the other arena). The reason for that is that unlike the first part, the second part wiped us pretty fast, thus it was hard to learn from our mistakes because we couldn't exactly grasp the mechs in their entirety. This took us two more tries.
The fifth time we came close but I botched us up. Turns out I've been messing up dodging the tail mech the second half all those turns (but somehow survived them) because I could not see (from my camera POV) where the tail was landing and I kept getting killed by it. The punishment window in that second half for tanks can spell death for the entire group simply due to how fast ahk morn pops up. On the sixth turn, I made use of my co-tank flexibility to move around freely and adjust my camera to avoid the tails. Those few seconds I spent not dpsing the boss and just simply wait for the tail to come up and dodge it meant that I was ready for ahk morn at all times. The other dps that turn also kept nailing that tail mech and honestly, I can say that turn, it was as if the entire group just played like true experts.
I'm not saying the sixth time was easy. It was still difficult BUT it was only possible to clear it because everyone persevered and to my credit, no one was trying to put anyone else down when they faulted. We only managed to improve at each turn. And no, that did not make us "no-lifers" for spending time on it.