I'd agree. As shws2014 says, it's "very disappointing, very annoying", and so it is. But as life says, "shit happens".
Sometimes you book non-refundable trains or digs, and the gig cancels. More often there's a clash of two on a given night and you've already bought your ticket for the second choice. Those who buy early train tickets for football matches will also be familiar with this, when they switch the date for TV and you're left with a useless train ticket.
Very disappointing, very annoying, but we move on.
Mick