Actually, that's EXACTLY what they think they can do. Assuming they can amortize the cost of mold development across enough figures (through a general release and a possible repaint or two), it's a lot easier for them to try and sell the "new and improved" version of those characters to kids, since they won't already have a toy of the character that looks like that. All the optimus and bumblebee figures (at equivalent scales, etc.) looked recognizably similar across all three movies (and probably intentionally so), despite significant mold differences (and mold development costs). That allowed them to appeal to the "new and improved" factor for the market, but given they've started to see "design fatigue" in that sales are slipping, the powers that be have likely decided that new designs are a way to reinvigorate those toy sales.
There's a point where it's cheaper to buy a new car than keep paying to repair an old one that's not running as well anymore. There's only so many times the old molds will keep selling and reselling before it reaches a tipping point where stock isn't being sold because kids already have a toy of that TF design already and stores are losing money. If stores lose money they'll not order as much from Hasbro, and so Hasbro will lose money. Considering just how many DotM and even sometimes RotF figures I still see sitting on store shelves here it's long past due redesigning those characters for new toys. But don't worry - Hasbro will probably milk those new molds for all they're worth for the next few movies.
I'm not against slight re-workings of character designs... but I'm really hoping they don't deviate a lot from the original aesthetics of the characters. We can see that Bumblebee's alt mode will be primarily black, but when he's in robot mode I want to be able to see that this is the Bumblebee from TF1, ROTF and DOTM. Same with Optimus... I'm really hoping they don't radically change his design, especially if he's the same Optimus from the first trilogy. In regards to other characters, I'm hoping the design for the robots doesn't change hugely. I love the movie aesthetics, the complexity and design of the robots. I'm hoping that any of the new robots in TF4 will have the same design aesthetics that robots in the previous films had. They should look like they could belong in any four of the films.
Vehicon Troopers would've been better than those protoforms we had in the movies. They never even transformed!
But still am really against having new design,maybe is just me. I guess it may take sometime for me to get used to it.
i'm a little against it too, like i said, i want them to spent the budget on making more design for the new bots
Think of it like any action movie. They spend millions to get Will Smith or Bruce Willis as the lead (plus more on wardrobe, makeup, etc) and then pay anyone base pay to play the cannon fodder enemies. Same goes for spending money on Optimus over Genericons. Now, if they actually spent some time developing the bad guys as characters, maybe there'd be some incentive to give them more detailed models.