In my case, I found Titan HM to be hard at first because I couldn't switch from moving and healing fast enough.

Turns out, I simply had to rearrange the 4 skills I used in Titan HM on my macro bar for faster access.
Then it became a piece of cake. I didn't even had to try to remember the rotation of Titan.

It took me a dozen of trials with different configurations to find out what I was doing wrong.

I think the learning curve of the fight is ok for the majority of players though.