I doubt people are suddenly going to start driving all the way from Kidderminster to London because they’ve lost a direct service. At most perhaps they’ll drive to a station on the other side of the Chiltern lines but as others have pointed out the connection from the local service is perfectly fine.
That's unfortunately not the case. The whole ethos behind various services (in particular, open access), is that by providing new connections, you'll generate a new market that otherwise wouldn't exist. The opposite is true if you take the service away.
Why? Because people don't want to go out of their way to take the train.
The competitive advantage of rail is always in part convenience. If you make journeys more inconvenient, you push people away. The vast majority find connections challenging and stressful (especially given the current ticketing climate, which is essentially fine first, ask questions later). Simply, remove the train and you'll loose your market.
Prime example? Look no further than transpennine express. Their recovery has been woeful. Sure, their performance has been far from exemplary, but the sub-50% pre-covid pax figures is miles below national (and regional) average and represents a far higher cut in patronage than the timetable reductions.
Welcome to a nationalised rail network - budget first, investment second.