It's been over 3 Years now since his damning nerf, and he's still overlooked for improvement simply because his ult has an opportunity to upset battles...
Just for some perspective...
v1.0.0.125 - 2011-09-14
Iron Man
Shield regeneration adjusted to 30% at all levels from 25/27.5/30%
Shield regeneration is now half effective versus minions
Mace of Spades bonus damage reduced to 65% from 75%
Siphon of destruction no longer adds additional shield for each unit hit
My biggest complaint is that they nerfed his shield gen 2 fold, and his early level shield gen hit the dirt, not because they did some anti-buff to his Iron Man passive, but mostly because they totally removed the bonus generation from Siphon of Destruction as well.
The explanation Riot gave about how he'd get more shield gen when hitting champions and less when hitting minions was total BS, they didn't even acknowledge the fact that Siphon was changed in the Patch Video, and the utter ignorance of pretending shield generation vs champions was gonna help or compensate in some way was ludicrous...
Minions don't avoid, Minions don't flee, Minions represent more targets and less threat, but most of all, Minions don't buy more MR. This might not seem like a winning argument, because it isn't, if they wanted to make Mordekaiser less passive and incentivize him to engage champions with more aggressive play, they should have given him the tools to do it. The problem is that they multiplicatively reducing his shield acquisition in virtually all scenarios, he doesn't have enough survivability to face foes and compensate for his lack of utility. If they wanted him to rely on aggression to survive, they should have changed Siphon of Destructions conditional Shield generation to Champions only, so if he hits multiple champions or at least some, he would be able to face opposition. Given that the lane composition consists of mostly minions and the map is mostly filled with NPCs, they should have been real about his passive too, 17.5 percent shield generation, and double on Champions, not the other way around... When you combine that with the obscured loss of shield gen on Siphon, and even a nerf to Mace of Spades just to be jerks, it's ridiculous.
Before that, he received a few buffs preceding his major nerf that were unnecessary, and increased his threat for no reason, the up front damage on his Ult and AP modifier on his Mace of Spades were not needed, and I'd rather they took that back in exchange for his defensive functionality.
There are a dozen ways they can repair this champion, some fear might fit his identity well, and some odd variation of CC immunity or what not would look good on his kit, but he was one of the very few champions with no mobility effects, and no CC, maybe the only champion with none of both, there was a reason he was impossible to bully in lane, because his kit did not permit him any recourse if he couldn't stand his ground. So that needs to be given back, whichever way they choose to do it, Mordekaiser needs to be able to stand in front of up to 3 foes and say, "I'm staying", at least long enough time for him to complete 2 rotations.
The fundamental loss of Siphons shield generation was that he can no longer engage a battlefield and get shield gen not only from a dense opposition, but it didn't matter how little damage he dealt, because he got a flat amount per unit hit, allowing him several defensive item choices.
Riot need to make this right, one way or another, I don't care what the excuse is, they can rearrange his power if necessary, especially since his ult is too convoluted anyway, I'd vote to remove all the complex transfer of power from his ult and put the raw power back into the rest of his kit... He needs to be able to stand in the center of a battlefield, be perhaps the hardest champion in the game to kill, and be able to choose from a mix of offensive and defensive items. I wouldn't be against adding hybrid ratios to more of his skills and some true damage, but we'll see... or maybe wait another 3 years >.>