The 787 was launched in 2002 and entered service in 2011.
The 3g spectrum auction in the UK was in the very early 2000s at about the same time 2g was being used by early adopters. 4g was a glint in the eye and has matured in recent years with 5g in the early stages of development.
The first internet connections appeared on commercial airlines in 2009 and they were (and still are) fitted to aircraft designed, in the case of the 737, in the late 1960s.
Aviation and electronics/telecommunications design and development move at different speeds so designing "in" the necessary antennae, electronic wiring, equipment bays on aircraft for the future is a bit of a guessing game.
I suspect the airframe designers are pondering the issue. Boeing keep talking (but not launching) about a new mid-market airliner and that seems to be the first design that will have an opportunity to design in appropriate antennae but I'm willing to bet that in 20 years time, if Boeing do launch the MMA, the fuselage will have a few unforeseen bumps/antennae.