Putting adult collector bias aside, the primary demographic for these toys are children. They are intended to be play things for kids. And kids typically engage in fantasy play. You may say that the majority of adult collectors may not engage in active play with these toys, but children are the majority consumer demographic for these products.
I think when appraising/reviewing a product (or service), we need to be mindful of the context of what the primary target market is and how well the product/service caters for its target consumers. In order to objectively appraise a toy, we need to look beyond our personal tastes and see how the toy can appeal or not appeal to different kinds of people, and particularly the majority demographic... which in the terms of Transformer toys, is children.
It's like say collecting those awful Keepers Trilogy Transformer novels. I only read the first book - hated it and didn't bother reading the rest of the trilogy. Now someone might buy that book purely to collect it as a piece of Transformers memorabilia and have no intention of ever reading it. They may say that the cover art looks really nice - which I agree, it is a pretty nice cover. And since they have no intention of reading it, they might say that as a display piece it looks beautiful, and therefore give it a positive book review. But the primary function of a book is to be read - to deliver a decent story, which IMO the book epically fails to deliver. Or some people may love Revenge of the Fallen because it has really great looking special effects and kick-bum fight scenes, which I'd agree with too - and because they have no interest in watching Transformers for the story, give ROTF a rave review. But visual effects are merely a story telling tool... the majority of audiences will appreciate movies with better written stories even if the visual effects aren't as fancy -- look at the way a lot of fans see the Star Wars Original Trilogy vs the Prequel Trilogy. Even in it's pre-mastered form with the visible strings and matte-lines etc., The Empire Strikes Back is widely regarded as a better film than the special effects bonanza that is Revenge of the Sith (though I personally like RotS, but I admit that TESB is gooder).
Likewise it's a basic expectation for a toy to be able to be played with. It totally sucks for anyone playing with RtS/United Jazz (child or adult) if say each time he moves his arms his bloody chest springs up (and head swings down as a result of the automorph gimmick). It completely RUINS the moment of the toy play.
Jazz: "See how you like my mighty punch, Decepticon!"
<deforms>
Cyclonus: "WAHAHAHAHAHAHAHA!"
Deformed Jazz: "Shut up! As soon as I get myself together, you're so dead!"
Cyclonus: "wateva"
<kicks Jazz over, transforms and flies away>
So whether you actually actively play with the toy or not, it doesn't change the fact that the toy is meant to be played with and that play is a core function of what the product is meant to do.