Only you would seriously propose, when a route has lost half its service, to remove the other half because people at stations which have two other trains per hour (minimum) might have to stand if they get on those ones or choose the other two. This utterly beggars belief.
*They are already having to stand* - that's before you try to force all of Oxford's passengers onto their services.
I fail to see why screwing up Princes Risborough and High Wycombe's services is acceptable, whereas putting Oxford passengers onto a coach for 30 minutes to Didcot and then having 8 or 12 car 387s running which guarantees them a seat isn't.
Just in case you hadn't looked - Wycombe's usage isn't exactly insignificant - pre Covid it was handling 3m passengers, add on Haddenham & Thame a further 1m and Bicester another 3m over its two stations and you're looking at the same number of passengers you see through Milton Keynes Central. With a much, much lower level of service.