Plus, the owner of the Android/iOS device is paying for that content anyway, why would it be in any way a problem if he can open that downloaded file in another software?!?!
I agree that DRM is a waste of time and the pirates are going to get the content whatever happens, but a $10/m streaming service is only licensing you to watch video in a few specific scenarios. If you had spent $3 an episode (or whatever it is on iTunes/Google Play these days) to own it, then I'd expect a DRM free file to be available (Though I doubt you actually get one in reality).