I believe many others feel differently, but personally, I find the Go mascot a bit scary. Dunno the reason, but it's something that I can't easily get used when reading the articles on Go.
FWIW, Russ Cox's GitHub icon[1] is similarly scary to me.
I've never been a fan of "creepy pervert gerbil" either. I wasn't familiar with Russ's even creepier rabbit-thing, but now the gerbil makes more sense.
The plush toy is cute, but it's the fact that Google monetizes an open source programming language by selling plushies that I find ridiculous
Well, since the gopher images are Creative Commons Attributions 3.0 licensed[1], you could make your own and sell them or give them away if you wanted. I think the point is to promote the language, not to monetize it, and making it available through the Google merchandise store was probably easiest for those involved.