Surely there are reasonable explanations. Let's break this down.
GPS and motion sensors. Why could they want this? Maybe they will switch up your play list when you go for that run. Seems plausible.
Contacts. Ok, everything is social, so maybe they want to send your current track to other spotify users in your contacts. Seems plausible.
Photos. Not sure about this one.
Sharing your information with partners. Does spotify play ads? wouldn't this be a standard part of sharing data with Apple and Google's ad network?
I'm not defending them, but this is the social world we live in. You either find alternatives or deal with apps that pack social features in.