I find it not very much in the style of sensible defaults not to include a Makefile.PL. To recommend such a "solution" in the face of the fact that older versions "propably have problems installing your module" defies the use of a module to handle the installation. If I wanted to create problems during installation, I would write the Makefile myself. If I give up installation to a module, I expect that the module tries its best to work in all situations. ExtUtils::MakeMaker works in all situations, while Module::Build doesn't unless I make special provisions, like including a passthrough Makefile.PL for compatibility.

Why can it be a design decision to make it easier for people to create broken distributions that won't install using CPAN by default?