2. Holistic Design
1. A robot mode that balances features of the alternate mode
There are two features that are conspicuously missing from this list.
First is CHARACTER. Why isn't CHARACTER an important feature of a Transformers toy? After all, Hasbro keeps recycling the same characters over-and-over-and-over. Character must be worth something, then.
I certainly would agree that character is an important part of what makes the franchise interesting for fans, and that character is often a major selling point. I would not argue that character is key to great toy design, however. Consider that all of the original Transformers began their lives not as Transformers, but as toys from different transforming robot lines. The characterizations that we know and love were developed AFTER the toys were already designed. Secondly, characterization doesn't necessarily have anything to do with the robot or vehicle mode of the toy. You couldn't guess the Function or Tech Specs of original Transformers just by looking at them. If Brawn was called Brawn, who would think he was the strongest Autobot? Who would guess the cop car is a Military Strategist or the bright yellow bug was an expert Spy? (Ratchet, though, was sort of a giveaway.) In the imagination, any toy design could be rendered into any character...so I wouldn't suggest character is a feature of the toy. Character is more about how the toy is marketed.
Second is ALTERNATE MODE. Why isn't WHAT the Transformer turns into an important factor? I agree that the alternate mode is important, but I don't think there is anyway to discriminate which alternate modes are better, at least not in a meaningful way. The great thing about Transformers is that they can turn into just about anything -- if all of the other elements are done right. Sometimes a Transformer is cool on the basis that he turns into something cool (race car, jet, tank) , but a Transformer can also be cool if he turns into something unusual (bi-plane, hovercraft, microscope), unexpected (UFO, city), or even funny (toaster oven, ice cream truck). But I would argue that these alternate modes as such don't make the toy any better or worse than another Transformer. A kid or collector might buy a Transformer that has a really original alternate mode, but they'll be disappointed if it lacks the other five features. On the other hand, some of most beloved fan favorites had completely unoriginal alternate modes. So, again, I'd list alternate modes as such more in the area of marketing than design.