So here I was marking my own reply (http://www.concrete5.org/community/forums/customizing_c5/uninstall-package-programmatically-uninstall-blocks/#378481) as the best answer and all of a sudden nothing worked anymore.

Typical case of missing graceful degradation in case a JS error pops up...

Symptoms: Clicking on any link with href="javascript: void(0)" results in *nothing* while I'm logged in. Other scenario's are yet to be tested.

P.S.: I'm at work and only had coffee!