So, yes, PoE is more complex, but only tedium comes out of this complexity.
A major advantage of the IE games - the asynchronous individual rounds of the IE games are waaay better than the impossible to follow irregular intervals in which PoE characters preform actions. This has a big role in making combat easier to follow in the IE games, and I used to tell this to Obsidian during the Backer Beta days. Let's take a "simple" (PoE "simple") example:
9 characters are on screen - a party of 6 and 3 enemies.
Character 1 has .9 s until he can take action
Character 2 has 1.2 s until he can take action
Character 3 has 1.6 s until he can take action
Character 4 has 2 s. until he can take action
Character 5 has .5 s until he can take action
Character 6 has 1 s. until he can take action
Enemy 1 has .6 s until he can take action
Enemy 2 has .8 s until he can take action
Enemy 3 has 2.3 s until he can take action
Your priest is Character 5. Your fighter is Character 1 and is near death after being hit by Enemy 2. You have no way to see either of these times, so you can't really tell if it's better to use your priest to cast healing on Character 1, or a hitting spell on Enemy 2. The indicators, while you are paused, do not give you any hint as to how long it will take for the recovery times to pass. You just see the lines, you don't know how fast either one of them is decreasing in length (one of the many glaring mistakes in the UI, but don't get me started on that).
In addition, if you are going to cast a damaging spell on Enemy 2, you have to take into account your chances of hitting him, because spells are based on Accuracy, but what if you are under the effects of a debuff, that lowers your accuracy? Should you: 1) Cast healing spell now, disregarding accuracy; 2) Cast damaging spell now, disregarding the debuff, or 3) wait for the debuff to pass and then cast the damaging spell?
This example uses just three characters and it's a pretty standard situation. So, who's volunteering to make all those calculations, in every battle? I thought so.