IMHO, it is a bad idea scrapping the call at Ashford! Ebbsfleet was designed to encourage people to arrive by road from the M25, A2, A20 etc rather than by train!
Ashford however, I suppose the fact that less trains are calling there, eliminates any potential conflicting movements if trains from Tonbridge direction want to head towards Canterbury! Aside from that, Ashford international had so much more potential than Ebbsfleet, as it is easily accessible from north and east kent, by rail and by road! The Marshlink services were extended to Brighton so that more people would be encouraged to use it!
From what i've read though in TR:UK magazine, Ebbsfleet is quite a poor service, as there is only a couple of shops which are never open, the station has a cold and uninviting feel to it, and the parking is quite expensive!