Looking at current state of some phpMyAdmin translations, I came to conclusion that some are not worth shipping, because they really do not translate reasonable amount of the interface. The problematic question is where to draw the line. For 3.4.0-rc1 I drew it at 50% of messages, what means that 25 languages currently pass. It might look too strict and the threshold will most likely change for final 3.4.0, but we need to start somewhere.
While discussing this topic on mailing list, Tyron Madlener came with idea to tell users of incomplete translations about it and point them to information how to contribute. I quickly implemented this idea and it is now in git and live on demo server. I deliberately decided not to remove incomplete translations on demo server, maybe they will attract new contributors thanks to new warning on main page.
Asking users of incomplete translations to help improve them seems like a clever and good addition.
You misspelled "by" as "bt" in remove-incomplete-mo.