Must say I've always found it a bit of a rigmarole myself and luggage trolleys should be able to go to the platform.......
I think there is a general presumption against allowing luggage trolleys on station platforms, on safety grounds - it's mentioned here in connection with the Edinburgh Airport Rail Link:
Q Will there be luggage trolleys available at the airport station?
A Yes. However it will be necessary for conventional safety reasons to prevent airport baggage trolleys from reaching the station platform
EARL Project Questions and Answers