My main comment is that the plugins should only be needed where and when they are needed. Making sure we have them installed can be covered by requires, build_requires, and (hopefully) dev_requires.
uuuhhhh.... no...
As I've explained a few times now requires and build_requires (and dev_requires/devel_require etc if we get them) can ONLY reliably be determined by running the Build.PL to resolve variations in dependencies on different platforms.
The dynamic_config: 0 "static config" option can be exploited to add the ability have build_requires modules installed before Build.PL is run, but please understand this is a hack, and not necessarily the intended purpose of the shortcut-dependency feature.
It also means that plugins won't be allowed if you have different dependencies on different platforms. Making a compromise like that is a decision Ken has to make a call on as the designer.
Adam K