Every minute counts.
HHE is a more useful junction station for the majority of passengers and operational flexibility in service recovery for the onward coastway connections. Cancel a coastway train from VIC - HHE for service recovery and you still have a connection for passengers from VIC. This logic does not apply for Clapham Junction and is therefore less useful for the vast majority of GTR passengers using the GX.
Okay, and the Preston Park people want Preston Park added, it's very useful for them.
And the Hassocks customers want Hassocks added, it's very useful for them.
And the Burgess Hill passengers want Burgess Hill added, it's very useful for them.
And the Haywards Heath punters don't want to lose their stop, it's very useful for them and others.
Of course, this is what happens in the peak. And what happens to journey times? It is destroyed. But, hey, I'm sure all of the people from Brighton, Preston Park, Hassocks, Burgess Hill, Haywards Heath, and Gatwick Airport all really need to travel to East Croydon and Gatwick Airport on an extra train above and beyond the current provision. I'm sure that's why the GX is so lightly loaded and this is the highest demand that is seen on Twitter.