But when you have been used to just jumping on any train that states its destination as "Swansea", "Bristol Temple Meads" because they all currently call at Reading is going to mean a change in behaviour.
All trains - really?
Nobody looks at the boards, you just go for the next fast and change at Reading. For a while the west country trains did not show Reading, but everyone got on them anyway as we all know they stopped at Reading and they have space to get on. That is space to get on, not a seat as commuters jump on the last minute, whereas long distance travellers are there well in time awaiting their platform to be put up.
The trend has been to reduce the number of trains not stopping at Reading, many went in December 2017 because of the need to avoid overcrowding. My local station had trains that skipped Reading during the peaks, but they left empty, so everyone had to cram onto a Turbo to get to Reading. I loved them when going to Paddington, an empty coach in the peaks! They now all stop at Reading and are much busier. This was because of severe overcrowding on other services, of which the GWR once had most of the top 10.
The reality is with capacity constraints most or all trains need to stop at Reading. You also need to remember that most real Reading commuters, that is those who commute to / from Reading come from the West, so if trains don't stop, GWR loose out.
I travelled on the last train that didn't stop at Reading, a HST. The guard and station announcements were continuous 'this train does NOT stop at Reading', but still in the rush people missed that call as they arrived just in time to jump on.