I was a Malz main before and the changes definitely hurt, but they were absolutely necessary.
Before Malz was downright oppressive in lane - if he was ever allowed to be strong he would have been immediately and swiftly nerfed down to old school Eve status.
They removed Malzahars early 1v1 - "I press R and you fucking die, thanks for the gold" and turned him into a mid-late game scaling champ. There was no way for a lane bully to have his ult and not present serious game health issues.
The rework had nothing to do with complexity and everything to do with fixing a champion who was actually, 100% for real busted.
As far as removing complexity I'm not sure I agree. It is now more important to manage your space aids and there is still complexity to managing voidlings (now it has more to do with harass / all in timings than push timings though).
If you don't think his damage was unsustainable before you are dreaming - they nerfed his base damage and scaling across the board and hard.
They took literally 100 base damage off of his E. Holy shit. Malzahar still deals scary mid game damage and his E used to deal 45% more base damage, never mind the scaling nerfs he ate on it AND the flat damage and scaling nerfs he ate on -every- single ability in his kit.
It sucks when a champion gets reworked and they become something they're not (from lane bully to late game dps), but Malzahar absolutely needed that rework.