By my reading of FHS, that is the only reason you
would
every want the /lib<alternate> format to be used in the first place.
However, if installing in /usr and your distro is one that uses /lib64 for libs in
general on 64 bit installs, I can see wanting everything to end up in the same
directory, but for installs in /opt, I just think it makes the directory look a
lot messier to have lib64 hanging around.
That is exactly why this PITA system exists: multi-lib support --- to install and run
32-bit software on 64-bit systems. One such app is WINE. For a long time the Adobe flash
plugin was another such beast. I think Skype is 32-bit too.
Darrell