The AI and peoples lack of control.
The biggest prob is that people order their pets to attack, then do something else while they think the pets take care of the enemy. A good MM always keeps his pets under his watchful eye and knows how he can issue orders on the fly to prevent a fight from getting pearshaped. MMs isnt about "attack", sit back, wait till mob is dead.. that will only get you into some dead pets and ultimately faceplants.
I already made some keybinds before MZ's guide was posted here and they are enough for me. Even if I wanted I cant use those binds due to the lack of available keys :P (i dont have a numpad). I only got commands for goto def, goto agg, goto pas, stay, swap to aggressive, swap to passive and dismiss all. Those binds are all I need to keep my pets under complete control (together with the 3 default macros you get).
"god, how many devs did hami have to sleep with to get ED?"
Total Cat @Stagefright
Im Robots my self and I find that concentrating them all on one target is best. Advantages of this is that you take down your target extremly quickly, one full volly is enough to take down a yellow on most occassions then qucickly move on to the next.
Going back to my previous post, the MM is supposed to be in full control of there pets as that is the whole point of the MM. If you sit back and let the extremly dodgy AI do the work for you you are not experiencing the full enjoyment if this very unique AT.