They only look silly because your used to seeing them without. If boxers and rotties have not been bred to have strong tails then maybe breeders should work on that as part of their list of things to improve
Interestingly enough there is a guy called Bruce Cattanach who has bred a strain of Boxers with natural bob-tails he did it by crossing them with a strain of corgi known for their natural bob tail and then crossed back to the boxer for a few generations, the KC allow dogs from this breeding to be registered as boxers.
how the f**k do you breed a boxer to a corgi.?tall/short di