Regarding Siemens: First of all, it's a surname. Second, nobody says "semens" when talking about semen, so it's not a complete homonym. Third, if they ever did have to cross that hurdle, they did it over 100 years before I was born. The company is older than my great-grandfather would be if he were alive today.
Google is a better comparison, but I still think it fails. Google is a homonym of googol, which means 10^100. The name connotes bigness, which suggests success. Also, as a mathematical term, it's suited to the very nerdy and scientific business of search engines.
Wii, on the other hand, is a homonym of we, which is the first person plural pronoun. It is clumsy to use it as a noun in speech. I cringe every time I have to say "Wii is" because it feels like "we is." We is not comfortable sounding like a dumb hick. We's accent does that already even without bad grammar.

What really flabbergasts me though is that Nintendo is fully aware of the problems with the name, but went ahead with it anyway. A good name doesn't have to mean anything, really, but Nintendo stuffed this one with so much meaning that it doesn't make sense without its accompanying speech. I don't want them to change it back to Revolution. I never expected that to be the final name. I really wish they would come up with something better, though.
I don't like the logo, either. It's bland and generic. Like the name itself, it doesn't stand on its own without an explanation. The ad campaign shouldn't have to waste time explaining what the name and logo mean.