I disaggree. Normal raids and trials look fine to me in terms of difficulty.
Failing a mechanic or dying is not an issue, and it's ok to fail a couple of (or even many) times before understanding and recognizing patterns. Don't go into a new raid expecting to play perfectly from the get-go. Allow yourself to make mistakes. No reasonable person will yell at you for doing something wrong.

If overlapping mechanics are too hard, only focus on one and ignore the other. One mistake will most likely not kill you, and healers tend to look after party members with higher number of vulnerability stacks (at least I do).

These raids are made with a lot of personal responsibility in mind, meaning one person screwing up will not lead to a wipe. As time goes on, more players will learn how to do the fights correctly, leading to less wipes. And to be honest I had no issue clearing fights via duty roulette in the first place. People died, sure, but only once or twice we actually wiped because of too many mistakes.

These raids are casual friendly because individual mistakes do not punish the entire party.

My bet is, many healers out there are also very happy with the increase in difficulty, because mistakes make their job more interesting and keep them on their toes.

Difficulty is and always will be a matter of opinion, and it's impossible to balance content in a way to satisfy everyone. If raids are not fun for you because you deem them to be too hard and not worth the effort to learn, then don't do them. The same way in past expansions people skipped them because they felt they were too boring and braindead to do.