Is it necessary to give up anonymity to become credible?
If such question has to be addressed (does it ?), is not the real problem authentication rather than anonymity ?

There are three documents which, according to me, settlle the debate:
For anonymity, by PRZ:
... http://www.stack.nl/~galactus/remailers/fallacy.html
... http://www.stack.nl/~galactus/remailers/fallacy2.html
Against anonymity, anonymous author:
... http://www.stack.nl/~galactus/remailers/no-fallacy.html
(I recommend the rest of Galactus's WWW)

I will just mention two examples illustrating opposite policies in the information gathering policy:
   -The (genuine?) tale with that old lady
         whose sole interaction with the outside world was the local newspaper's obituary.
        She was reading everyday the only news of interest to her, which made her day brighter: she was not there.
   -The system Echelon which collects all global telecommunications
    or more simply the legal obligation in France to deposit all printed material at the 'Biblothèque Nationale'

Let us hope most people have an intermediate openness policy,
    half way between total censorship and indiscriminate accumulation.
The rules are everyone's decision, according to mind openness and time available:

I like to read over and over again my favorite authors, from Baudelaire to Gide or Camus.
I also like to find ideas and styles which are new and thought-provoking.

On the other hand, about softwares,
    I would not install a software without PGP authentication before I performed a complete virus+trojan scan.
    (well: in the other case too.... say I would be more confident)

And if it just an informal discussion about a leisure subject,
     I will just run away from any contributor who would insist on his name, titles, functions, military resume...
        before he will try to enforce his tastes and distastes about everything..