Hello Daniel,
I don't think this UI was really ready for criticism yet :). Please be a little patient, at this time Joerg is just trying out a way to implement the required feature set, we can always make it prettier later. And the required feature set does include the capability for multiple quality types / different dimensions, even if the use in the de.wikipedia case might be very simple at first.
So I advocate for a system that is not too generic in a technical way and which consists of single click through flagging (on diff view).
Joerg has a specific set of specifications to work with; these will be implemented. Flexibility on the backend does not make it impossible to implement UIs for specific use scenarios.