Panniers are very luxurious for the reason you cited. Where they fail me is when trying to combine a bicycle leg with one by bus or subway - the backpack wins i

Panniers are very luxurious for the reason you cited. Where they fail me is when trying to combine a bicycle leg with one by bus or subway - the backpack wins in these cases because I don't need to remove/re-attach my Ortlieb pannier (which gets to be really annoying even despite Ortlieb's really nice quick release mechanism on their urban models).