The TFwiki page explains why redecos are important for the brand. As others have mentioned, it helps to keep the cost of toys down. Why a Diaclone redeco? Uh... what other redeco did you have in mind? Killing Jar colours? That's just as obscure. With some figures there really isn't a whole lot of redeco potential.

And HasTak are getting good at planning redecos from the outset by gang moulding alternate parts together instead of going through the expense of retooling existing moulds, which can be quite restrictive as seen with the MP Coneheads (especially Dirge). The MP Nissans, Lambos etc. were concurrently gang-moulded together, allowing each one of them to have distinctive mould differences without needing to retrospectively retool the moulds. You can bet that MP Inferno has been gang moulded with MP Grapple components. All of this helps TakaraTOMY to release more figures and the redecos help to keep the cost down.

You'll notice that most of the toys that TakaraTOMY have already done as MPs are the ones with obvious redeco potentials. The next one would be Trailbreaker/Hoist, but beyond that the remaining Autobot Cars don't have well known redeco potential. Jazz? Mirage? Hound? Sunstreaker? Skids? Hound can be redecoed as MP Detritus, MP Skids as MP Quantum Operative Skids, Crosscut & Screech, and Jazz could be redecoed as MP Stepper. But what about Mirage and Sunstreaker? Beyond releasing them in their Diaclone colours with new identities, I can't think of what else you could do with those moulds (I think that Sunstreaker in his Diaclone police colours would be neat ).

And as others have said, you don't have to buy them all.

Quote Originally Posted by Trent View Post
Yeah life's tough huh? You do know there was a time when we were lucky to get one MP release a year right? Now we get one a month.

#firstworldproblems
↑THIS!