just some thoughts:
regarding reinventing the wheel - i've written a template-system once (now i don't use it anymore, there are much better ones), i've written my own XML::Simple extension which did something extra (i could have just used another module because XML::Simple is designed to be simple), and i'm writing my own framework now although there are already some (well i started to do this before there were really usable frameworks).
i think it's necessary that people are reinventing the wheel. they learn, and maybe they learn that it's just better to use an existing solution. maybe the write a better solution, and that's good.
without people doing that there wouldn't be so much solutions to choose from. usually at some point there are three or four solutions which come out as a standard, e.g. use HTML::Template, if you want an easy solution which is easy in both using the module and coding the template.

when i'm coding something, even if it's a small program, it also helps me to encapsulate things in modules (especially in OO). i don't do uml specs (when i'm coding alone), so i think about what functionality i want, and create a class. if i want more functionality i usually first use it in the main script like $object->do_unexisting_functionality() and then add this method to the class. i just find it more maintainable. but maybe that's just a personal preference. just my 2 cents.

Update: about too much modules - i recently installed Maypole. i did perl Makefile.PL etc. for every single PREREQ_PM. i didn't count how much modules i installed recursively on that afternoon, but it was incredible. lots of the required modules were probably just optional but were in PREREQ_PM, so i maybe installed 20 modules i will never use. but hey, disk space is cheap ;-)