Ugh. If you're writing enough code for strict and warnings to be useful, then adding "use strict;\nuse warnings;\n" to the top shouldn't be too hard. Fortunately, the people who have enough skill to modify the Perl core don't share your opinion.
No, it doesn't and it just as well shouldn't, but could. I like strict and warnings in use in my code, because it means I'm less likely to create a maintenance nightmare for myself. But as far as other peoples code, they can create as much of a maintenance nightmare for themselves as their heart desires. ;)
Just add a use Moose; at the top if your script and you too can have strict and warnings on by default for whatever package you're in. The next logical question that I'm at, is if Moose further cuts down dev/maintenance time how too can I avoid this redundant step of useing it. There isn't an easy answer that will allow you to maintain backwards compatibility but shipping Moose as a core module would make widespread development a reality.