Why is it "mean" to improve someone else's work? The only hope for CPAN to "scale" is for this attitude of "Don't touch my/his/her module!" to go away.
We all have blind spots. In my experience, the best software has been touched by several hands, each making improvements that the previous author was (relatively) "blind" to.
Also, once one succeeds at the challenge of getting a module working well enough to bother to upload it to CPAN, the motivation to work on it will typically decrease, often by a large amount.
Your first choice should be to improve an existing CPAN module. The idea of taking your turn at "taking over" the module should not be an unpleasant thought. Nor should the thought of letting someone else take over for you (if you aren't up to directing the merging of their improvements in). I'd think that most new authors would allow previous authors to have influence on the module if they wish to.
Try to think of the greater, common good. Be respectful of each other and of the history/heritage of the module, but please don't run away from making one really great module instead of yet another similar (better in at least some ways) module such that it just continues to get harder and harder to pick which module to use.