[arghwhat]

SNR is not a function of antenna size. The size is dictated by the wavelength, not how desperate you are to receive a signal.

Directionality does make an antenna larger as it usually involves reflectors and directors, the size and placement of which is also a fraction of the wavelength, but if they are actually able to do direct to phone with decent reception and arbitrary coverage, then that beats having to set up base stations to cover a small circle even if you get 10-15 dB better SNR.

This might give you LTE in, say, all of the Australian outback, all of Alaska, along the Andes mountain range, etc.