Until PBP, there was not a single Perl book which had focused on writing better standardized code.

Although I agree with your overall point, I must stand up for one of our own, Merlyn, whose work with Hall on Effective Perl Programming was a great help to my Perl coding skills. It's a book very similar to PBP in a number of ways, although it's not as comprehensive; it's sort of (in my mind) a cross between PBP and Perl Cookbook, and (if I recall the latter's pub date) pre-dates both.