Maybe that's why all the other HMs are easy for me? We started with HM Esseles. Ironfist took a few tries, but once we figured it out it was all easy.
Don't start with Esseles, it's one of the harder HMs. Also, ops before that.
I do agree though, that adding stringent enrage timers to every encounter is a poor way to design. So far, that seems to be BioWare's solution to "making things hard." I've never seen an enrage timer used a boss mechanic (besides anti-cheese) before.