[bregma]

The potential station in Georgetown was skipped for geotechnical reasons. The original town was sited on an enormous and very hard rock above the river and surrounding swamps and that made blasting the huge station cavern prohibitively expensive. The running tunnels are already extra deep there to run under the Potomac.

[snowwrestler]

The Rosslyn station is directly across from Georgetown in the same geologic unit.

[midoridensha]

There's already plans for a new line that will have a station in Georgetown.