Since Crossrail prides itself on running to/from London and Reading why is this critical information missing from the displays? Reading is a major hub for interchange between local trains and Intercity / Cross Country services. It is vital to know when local trains arrive there. Why is this information kept so secret, or is it incompetence by Network Rail / T4L / MTR et al. I would opine the latter.
Does this situation pertain at other Thames Valley stations?
Where do you think you've seen it shown? The current (and previous) platform displays show station calls in the running text in line 2, and in most cases without times. I'm sure I've seen some places where times are shown, and that would be "just software" - mostly in assembling the data from wherever it's kept. However, showing scheduled times would raise issues with delayed trains, and showing predicted times would raise further issues (e.g. how good are they and how do you indicate what they mean). So I can understand if leaving this off is preferred.
Concourse displays rarely show station calls, except on the bank of one-per-train ones in a big terminus. I think I've seen those with times, but I've no idea where or when. The ones in London terminals now don't have times, I'm sure.
As to printed timetables, I wonder what you mean.
GWR▸ 's full line booklet (T10) shows all trains going to Reading, but may not be on offer at
TfL» 's stations (and not necessarily put out in GWR's ones, of course). TfL rail's one does, I think, show all theirs plus GWR's stoppers and a couple of semifasts (only if they stop at Slough). However, I've never tried to get one - I'm not even sure they print them, though the PDF looks like it's designed to.