He has a point really. The mechanics of most boss encounters (outside of EC/LI at least) are fairly simple and 99% of all bosses have short enough enrage timers that raw dps is a major factor in whether you can kill them or not.
Newer content like Lost Island (and i assume EC) has better/varied mechanics but it's still hampered by the UI's lack of details to let you know whats actually happening.
To use WoW as an example, you can go into a new boss fight you (and your group) have never seen before, wipe due to not knowing the bosses skills etc (ignore the new fangled dungeon journal for this

) then can sit looking over the combat log and slowly peice together what killed you and why.
In SWTOR you can't easily consult the logs to figure out what a boss just threw at you so inveitably the mechanics end up simplier.