I think you should focus on the improvements to rail links in the offing - ELL, potential Thameslink routings - rather than the disappearance of the direct train to Charing X. It's easy enough to change at London Bridge.

"South central" London trains are supposed to go to the terminal shed at London Bridge, just as trains on the Sevenoaks and Dartford lines and out to the Kent coast are supposed to pass through London Bridge to Charing Cross or Cannon Street. Leaving aside the more subjective argument that if you've come further, you've a better case for a direct service rather than having to change, any change in the routings above - i.e. "south central" trains through to Charing X or "Kent" trains to the terminal shed - means at-grade crossings and more conflicted train movements. This in turn reduces network capacity at what is already one of the worst bottlenecks.

Worth bearing in mind the bigger picture - like the railway companies are doing, like it or not.