Signatures Provide Context

Signatures give useful lateral context and create an InternetEconomyOfCredibility.

In other words, signatures mean

"I wrote this"
that when someone goes to your HomePage and clicks on the title they can find everything you've written.
that people can easily get to your HomePage by clicking on the link formed by your name. Once they get there, they might leave you a note. Or find and use your email address.
that other people can quote you by name and cite your work in their footnotes.
that people's opinion of you will be influenced by their opinion of your writing and vice versa.

On the other hand,

not signing means

that prejudices won't affect what you've written
that Wiki will not turn into a PissingMatch
you won't make any enemies (or friends, for that matter) on Wiki

Each time an authors signs a comment, they wager a little bit of their credibility. With each "good" thing written, other authors re-enforce the idea that the poster is "smart" or "insightful" or something. With each "bad" thing, it makes other authors more likely to "flip the bozo bit" and maybe start ignoring statements out of habit.

If KentTheBeck writes something, and the reader's thought is "What? That sounds stupid" .... Wouldn't most authors around here read it again, and try a little harder, before deciding it is just a "dumb" comment?

-- EricHerman