AA currently offers GOGO WIFI--two weeks ago just reading emails was slow, they even note that "streaming" is NOT supported.
Even with fast(er) WIFI, not everyone owns Laptops etc., so that those pax will be left to read only AMERICAN WAY magazine for several hours.
There is a difference. The plane to ground via cell network connectivity is slow and cannot handle the capacity of 50%+ of the plane connected to it.
The streaming entertainment is provided by servers on the plane and the wifi bandwith can handle that workload for the most parts.