X-33 Venture Star: Was cancellation a big mistake?

It looks like pretty impressive tech, but I am not convinced of the aerospike engines, and the cost benefit wasn't as big as SpaceX is claiming to be able to do.

Anyway, I was for the project, despite the possible flaws.  It could be that the aerospike engines are really better, but the ISP numbers don't look any better, but actually worse than the Shuttle's main engines.