Isn't this just a symptom of change culture?
You have a system that provides a service; it's a bit slow and dated but generally works. A consultancy is brought in to give it a revamp. What happens next? Do they advise getting a bit of new kit and refresh of the front end for a few hundred £K and minimal commission? Of course not, they're looking after number one! They're going to insist you need to rip it all up and start again, with no attempt to keep the best parts of the legacy system. Indeed, backwards compatibility with the legacy system will be deliberately obstructed so you can't run the new system in parallel and compare the two. The new system will be hailed as a great success, with no objective evidence. The consultants will walk away with their fat commission, the senior management will walk away (to work for the consultants) with their fat bonuses. When the whole house of cards comes crashing down, the new senior management (who used to work for the consultants) can claim it was all the fault of the previous management, then a consultancy is brought in to advise on how to sort out the mess. The whole cycle starts again and no one is ever held accountable.
It's enough to drive you to drink!