Both Reading and Basingstoke are busy and rapidly expanding towns, Bramley has also seen considerable expansion as well with a large new housing estate under construction next to the line in the North Western side of the village. It also helps that both Basingstoke and Reading are notable interchanges as well. Between the Peak Hours, it's busy enough that GWR has justified a 3rd service. It will also soon have Green Park, and potentially, the long talked about station at Chineham (north eastern suburb of Basingstoke with a large business park) added as well.
You will also see a considerable number of passengers who, despite having to stand, will take the XC service in the peaks simply to avoid the all stops - despite there being a 5 - 10 or so minute difference in journey time. It's certainly no rural backwater, and one that in my opinion, should have justified being wired up at the same time as Reading to Newbury was.