If TDO had a better track record I would most certainly agree with you, but since there is a trend of serious cost cutting and eliminating entertainment, I don't see how theorizing that Disney may not have offered a reasonable contract is nonsensical. Is that definitely what happened here? Who knows, but it wouldn't be all that far fetched.
Disney definitely has the upper hand when it comes to contract negotiations like this. As a musician who has been involved in contract negotiations for many gigs, it's not hard to figure out your value as a performer/act and what a fair contract would be for both parties, especially if you're the British Invasion and you've been doing it for over 15 years. Trust me, if you're a musician/band, you don't turn down a stable and steady gig like that if the money is even remotely fair.
The fact that they are willing to walk away from one of the most stable gigs a musician/band could ever ask for that requires minimal travel and rehearsal tells me that more than likely they were not offered a fair deal. To leave Disney, they must feel it's worth the risk and effort involved with dealing with multiple venues with less consistent scheduling and the uncertainty of contracts that are much shorter in length.
Now like I said, is it possible that Disney isn't at fault here? Absolutely, and I really hope that this isn't another instance of management tightening the purse strings. However, based on their track record, I don't think it's unreasonable or nonsensical to discuss and debate the possibility that the British Invasion is just another casualty of cost cutting, especially since it's something that we see more and more these days. Just my $0.02.