Laz
Developer
I was going to say something like 'The core engine seems fine...', but that isn't the case, and is likely the root of the problem. It would be very very difficult to ensure compatibility between the existing engine and one that was re-written, since even minor implementation differences could likely lead to radically disjoint game states. Hence, as Wizards, you can't simply go 'this engine needs re-writing, it has some pretty crippling performance limitations' without also going 'everyone out of the old client! New client coming through!'. Trying to ensure that the new version is backwards compatible with the old client makes it very difficult to fix the problems of the older client (which are mostly engine related, as opposed to UI related I feel).