fourthreethree
I guess you do not work in a TMA/busy environment.
Expedite is certainly OK for use in the world of NATS.
In the London TMA, many departures offer ' a good rate on first call' and may be hoping for an expedited climb to give them a short cut.
I do not wish to criticise anyone, but there is more than one way to do the job of ATC.
Using 'expedite' a few times a day, makes my job much easier to perform.