Toshio Kuratomi (a.badger@gmail.com) said:
Personally, the more i think about it, the more it feels right and makes sense to allow this. In essence, one can consider non-multilib'd %_prefix/lib and %_libexecdir content to be equal policy-wise.
I've thought of one technical thing that is lost if we allow this but it may not be that important. Currently a sysadmin could install packages on an x86 and then mount the /usr/lib directory on both x86 and x86_64 systems. This is similar to the rationale the FHS uses for splitting /usr/share/ from %{_libdir}. It isn't in the FHS, though, so we aren't required to to keep this feature.
This implies sharing /usr/lib separate from /usr/libexec, /usr/bin, and so on... I think that's pretty far into the fringe of use cases, and not something we really need to support.
Bill