You mean like the mediocre NRE app - the lowest common denominator that upsets the fewest. I simply don't understand the mindset that sees centralising as the answer, and assumes that a central body must deliver a better product.I agree. This is actually one area where it would be sensible for all the TOCs to work together and develop a single app, which could then be customised with their branding and possibly also add-on modules (e.g. around catering, etc). There really is no logic in reinventing the wheel. Of course this does happen already to an extent - there are several apps which are used by multiple TOCs with their branding, but all of them which I've used have their drawbacks.
I've had an invite from LNER to test their new app (I've declined due to not travelling at present), and it's clear that they are trying to do something that works for their customers, using the app to build relationships with their customers.
I've no idea whether it will be good, bad or awful, but I'd be very wary of an approach that treats rail customers as though we're all the same. I'd be even more cautious of that being done by some background organisation, that has no direct connection with the customers who actually buy the industry's services. The experience of Railtrack/Network Rail shows how that disconnect works against customers as the focus shifts from supporting the front line business to a narrow focus.