A week or two ago, I configured a newer version of CPAN.pm than I have ever used. Don't laugh if this is old news, but one of the configuration options that were new to me involved the choice between Makefile.PL and Module::Build.
I have written modules that use Makefile.PL, but never Module::Build. I'm peripherally aware that for backward compatibility Module::Build authors often supply a Makefile.PL that I think is basically a thin wrapper around the Module::Build process or something. I don't trouble myself too much with it. CPAN.pm usually handles this just fine for me, I'm sure that Module::Build is the wave of the future, and I will learn about it when the benefits I'm aware that it provides exceed the cost of learning it, which is to say, "some day."
I think this configuration option wanted me to select which method I preferred in situations where I had a choice in installing a module: if both a Makefile.PL and a Module::Build are present, which one would I prefer to use? In retrospect, it seems to me that this is a decision best answered by the module author, not the module installer. I'm certain that in every case one of these options is better maintained than the other. And I suspect that for many modules, one day the difference in quality between the well-maintained and the less-maintained routes will be enough that one route will cease to be maintained for that module.
So it seems to me that it would be nice if Module::Build files and/or Makefile.PL files could have a new option added, one which specifies which installation method is the one preferred by the module author and is therefore likely to be more maintained. Then CPAN.pm could check this and try the better maintained route first. Personally I don't care which method is used, as long as the installation is flawless and the module solves all of my problems including world hunger.
Of course, getting this option into Module::Build and/or Makefile.PL and CPAN.pm has a cost, and the cost involved might be so much that by the time it is spent (it is likely to be a time cost) everybody will be using Module::Build anyway. But it was something to think about.
In retrospect upon completing this post, it dawns on me that the best thing to do is teach CPAN.pm to be aware of some new third file which will indicate the installation method recommendation in some machine-readable way, rather than mucking about with Module::Build itself.