Im assuming you mean the 18:20 Euston Birmingham New St service. Why would you want a text telling you which platform the train is going to depart from? There are massive departure screens at Euston. Has it got to such a stage that people are so unaware of their surroundings that if their mobile phone doesnt tell them something they cant function?
Sometimes it's nice to wait somewhere that isn't in the middle of the enormous throng below those screens.
I had a trip to Liverpool on Tuesday and thought the text alert worked well - I got an alert about a minute before the rush started.