My disappointment comes from the fact that there are stations where the Piccadilly just blazes through and doesn't stop. The platforms are there, maintained and in use, but the train just goes past. Those areas have been repeatedly told for the past decade "no new stops until signalling upgrades which you'll get when the new trains come – otherwise it would make the journeys longer and we can't have that on a line that services Heathrow!".
Now the time has come and the signalling upgrades were axed, meaning according to the original logic, no chance of getting the trains to stop at your station. Of course new stations could be serviced, at a cost of making the journeys slower – surely the argument of "if the train stops at your station, it'll slow down the journey for everyone" applies to all stations, not just a select few? But even if we go with the nonsensical "we can't slow down the average journey time", other options could be taken, such as making the trains stop at the least used stations alternately – you don't even need to go full "Express Train" route NYC does if your issue is just a couple of stations.
Still, TfL hasn't really shown any interest in touching any that and always said "you'll get your stop with the new trains". Well, the new trains are almost here and it doesn't look like it'll come with a solution, just more of the status quo.
Air conditioning is of course great and I'm not advocating for maintaining old stock forever. But a shiny new train does nothing if the train won't stop at your station. And you're not going to get much gains if your shiny new trains are effectively throttled to last century speeds with last century reliability.