One very practical consideration for using as few modules as necessary (while still using as many as you absolutely need to) is bloat. Bloat bites you in two ways. One is size: pull in enough modules, and pretty soon things like the profiler go haywire. The second is startup speed, which doesn't sound like a bit problem when you're doing a mod_perl app, unless you're heavy into unit tests, in which case the startup hit for pulling in several tens or hundreds of modules bites you every time you execute a .t file. And when you have several hundred tests (a good thing), the additional startup can add minutes to a full test run (a bad thing).
Code reuse is not an absolute good that happens in some ideal vacuum. Reuse is a tool, and like any other tool, it has both benefits and costs.