Seems look it would be harder to tally the votes without knowing the names.
This is for an automated system. They'd be handled internally but not visible to other users.
As for pros and cons, I guess they'd be something like this:
Anonymous:
Pros:
You could vote freely without having to be concerned about what other people think of what you're voting for.
Cons:
Might be harder to identify potential "voter fraud" if the whole community can't see who is actually voting.
Not anonymous (onymous?):
Pros:
Curious users can see who all is for or against different features.
If something sketchy happens, it will be more apparent who caused it.
Cons:
Some people might feel pressured into voting for or against a feature when it's not really what they want.