outburst without substance?
if you have no idea what you are talking about, don't do it. if you never had a problem you are probably not deep enough into it, and you obviously never looked into the differences and accepted the wrong defaults.

copy was the simple idea of perl IO copying, block per block, allowing handles, but it did not care about OS specific settings, like preserving permissions or ownership. This was a big issue over and over and p5p never cared. This was fixed finally a few releases ago (2.15 exactly), but there are still older perls around which use the old simple copy, loosing file attributes. The problem is mostly in os-compat Makefiles, which does use ExtUtils::Command cp for copying files, i.e. executables or shared libs, which loose there x bit after that treatment.

syscopy uses the system provided syscopy and preserves attribs on most OS, and cp uses the cp(1) utility with filenames, if available.