Another bad point for CPAN: nowhere in the installation is the presence or absence of the htmldoc program tested for, or even mentioned. There's even no standardized way in the MakeMaker utils to list it. It is a dependency, isn't it? It's the same with external libraries, those dependencies aren't checked either. ("probably harmless", yeah, right.)

This dependency is the reason for the huge amount of test failures on CPAN Testers. But if you don't look at the report very closely, you won't even see what is wrong. This is very user-unfriendly, for anybody who isn't at least a sysadmin by profession.