I think its funny that people simply site the Tumbler, the ED and the PL and say "Why can't HT just make an Iron Monger?!?!" Not a shot at the post above but I've read that over and over. Look, there have been companies who have made 1:6 remote control cars forever, even the Tumbler, what is shocking is that its functional in terms of being able to put Bats in there which wasn't the case for those other companies but in terms of scaling it isn't a groundbreaking thing. PL, ED both great in their own regards but let's look at Iron Monger's constructs.
The legs are on balljoints for movement on the figure but if you look at the pic from the film
The legs are narrow and short making it difficult to actually make it function and get a Stane in there. Not to mention the shoulder angles would destort a 1:6 figure in there and get him to still be able to be some what posable.
So let's say they go No Stane. Just an IM. Okay, the Iron Monger that SWS made was 10' in 1:6 world that's 20". That's 3" taller than the PL not to mention hes about as wide as the ED-209. So you take the size and say we've gotta make it as posable as Iron Man and you've got quite a task. Not to mention that the Iron Monger in design is amazingly top heavy so you've got to measure out the balance in order to make it be able to stand without looking grossy misproportioned because if not he'd topple every second he is left alone.
Its not easy of a task by any means to do it and then make it affordable enough to where people aren't gonna go "For a figure? Really?" and actually order it.