If the main issue with a long term stop at Turnham Green is the
increased journey times for Piccadilly line users then i'm all up for
replacing the stop at Barons Court with a stop at Turnham Green.
Barons Court and Turnham Green may have similar entry and exit numbers
but Turnham Green is at a point where the district line divides and
hence it has potential as a very useful interchange stop. If I'm
travelling from Richmond, Kew or Gunnersbury on the District Line and
need to travel West on the Piccadilly Line, this currently requires me
to first change on to an Ealing bound district line service to Acton
Town and then change on to the Piccadilly Line from there, adding
10-15 minutes to my journey. Likewise, if a traveller is on the
Heathrow or Uxbridge branch of the Piccadilly Line going east and
wishes to travel on the Richmond Branch of the District Line they also
have this time wasting double change.

Let's not forget that Richmond is a major station, Kew Gardens a major
tourist attraction, and Gunnersbury an important business location and
a link with the Overground. The Piccadilly lines mentioned above also
have a large number of stations and a large catchment area including
Heathrow Airport. So this 10-15 minute time saving could translate
into a big overall time saving for a lot of people.

A stop at Turnham green would also benefit Chiswick Park, Richmond,
Kew and Gunnersbury east bound travellers who could get on the quicker
Piccadilly line going east at an earlier opportunity, the Ravenscourt
Park and Stamford Brook west bound travellers who could get on the
Piccadilly line going west at an earlier opportunity and of course the
Turnham green residents themselves:-)

So overall, a benefit to lots of people compared with a disadvantage
for the people at 1 underground stop (Barons Court) who will still
have two District Line services and a 1 stop west/2 stops east easy
change on to the Piccadilly Line.