Your thinking about it the wrong.
Right now most people dont have crazy fast 4G OR LTE speeds and most people do not have unlimited data, so even in a perfect world if all phones had the fast data speeds possible , people would still complain about the cloud and not having unlimited data plans to access there things whenever they want and as often as they want.
Having things cloud based is about having all your particular service weather it be music, videos or pics accessible to you no matter where you are or what phone/tablet/laptop your using and having all these things SYNCED across the board. I could have a 128 gig sd card on my phone right now with my favorite album in the world, but lets say i go on vacation somewhere and i left my phone back home, all of a sudden i want to listen to that album, only way i can access it? Using a cloud based music service. Sure i know what you thinking well even if you had your phone with you and you only had the album in the cloud without a data connection you couldn't access it , but finding internet service is a lot easier than finding a data connection if your in a place where u dont have it
Using the cloud is about convenience for the user. depending on internal storage or a sd card or any other hardware based storage option is slowly becoming less and less convenient