I have always thought it's really daft for Beeston passengers travelling to London to have to use the slow train, or change at East Midlands Parkway (which is actually still quicker overall than using the through train). If it were up to me I would definitely say that enticing more people who use Beeston onto the fast train would be more successful than enticing long-distance bus passengers.
Against this, I really love the idea of genuinely low-cost travel challenging budget airlines and groups in their car. Making use of rail and coach packages seems like an excellent way to do this, because the coach routes can be provided at very low cost. The problem arises because EMT and soon EMR are not really a budget operator at all. Nor really would we be well served by them becoming one. Indeed this is something the UK mostly lacks - Hull Trains never tried to be low-cost and Grand Central tried but have kind of given up. West Midlands Trains is the only really successful example of long-distance budget rail operation, although Northern have tried to muscle in on short and medium distance routes with reasonable success. If a bus coach service were to be run connected with WMT services to London, that would probably be a genuinely low-cost operation. For example, a coach service from cities in the East Midlands and Yorkshire to Rugby, for WMT services to London Euston, would probably be able to be packaged at a market-beating price given the huge availability of bargain tickets from Rugby to London that currently exist. There is no real reason to believe WMT might try it, though. There are also some capacity implications.