The train operates up to an hourly frequency with journeys taking as little as 2:50.
The train has multiple pickup points at Morpeth, Newcastle, Durham and Darlington and takes you're direct to the centre of Birmingham. In isolation the train likely has a larger catchment too.
You need to travel to the airport and park up. Travelling to and from one of the mentioned stations is quicker and easier for most.
You also have the benefit of turning up and departing on the next train (ticket type permitting) and XC trains allow you to text and book a seat ten mins prior to departure.
I'm surprised it lasted for so long.