All credits to you for just thinking about it. Being aware that you put a burden on downstream users is a very nice start!

Points to think about: when depending om somethink like Moose is directly and indirectly depending on a whole bunch of other things already, so adding Path::Tiny is not that much of a problem anymore. It is more than likely that one of Moose's requirements already depends on it anyway.

The second thing to think about is how much back you want to support perl itself. 5.005? (probably not). 5.6.2? 5.8.4? 5.10.1? 5.12? Some modules you want to depend on (or like to use) might not support the perl *you* want to support.

Another thing to be aware of is the number of modules that already depend on the module you want to depend on: the position in the river of that module. The higher up-river (like Test::More) the more likely any of the other modules already installed on the system already depend on it: the chance that it already is installed is higher.