Only difficult if you have a vested or self interest, in fact you'll try and find every reason why it shouldn't happen under the sun, so you're not inconvenienced.
Sod everyone else who pays more. You want to travel on IEP(HST) which are in GW terms premium services as they have limited capacity, so they should attract a premium rate for those who want to go to Reading.
Supply & Demand.
Supply and demand indeed - and the fact of the matter is that the supply of rolling stock for GW services generally, but especially in the Thames Valley, has completely failed to keep up with increased demand for travel by rail, from Reading and everywhere else.
While pretty much every other major route into London has got extra rolling stock in recent years, until the first Class 387s started running, GWR was pretty much operating with the exact same fleet on inner and outer suburban trains that Network South East had in 1993 - which also has to cover work up the Cotswold Line and Reading-Gatwick.
Some tinkering around the edges has been done, such as HSTs on some Didcot and Oxford outer-suburban duties and the return of a few Class 180s, plus leasing the two 150/0s, to free some Turbos for suburban work, but that's about it. So GW has done the best it can with what's available - and that includes using long-distance HSTs to help shift people in the Thames Valley.
It's not just Reading where there is high demand. The 17.49 to Worcester, which had some seating capacity to spare, has called at Maidenhead for some years now to set down commuters there.
A perfectly logical use of finite resources but it appears you'd prefer that the train left London in the middle of the peak with lots of empty seats. Where's the sense in that?
One of the timetable changes from January sees the 17.49 path taken by a 387 to Didcot, with its first stop at Maidenhead, with the Worcester service moving back to 17.52. Even with a switch to the relief lines and a call at Twyford, the 387 gets into Reading at 18.23, just four minutes after the retimed Worcester service. I'd expect GWR will be making every effort to encourage Reading passengers to take that train, along with the people headed to Maidenhead/Marlow and Twyford/Henley.
Maybe you might just give GWR the benefit of the doubt, now that they will soon have more rolling stock available, and wait to see what effect the timetable changes in January and again in December next year have on people's travel habits.