Hmm - it's easy to criticise the design after it was built. Yes, the design was bastardised: the payload bay was changed, the launch configuration, the re-usability. The feasibility study used a completely unrealistic launch rate. However if they didn't build to the available funds, it wouldn't have ever been built (presumably).
That being said, the STS wasn't a lemon. In both cases of disaster, there were warnings regarding hazards that were ignored and could have possibly been mitigated against.