For many reasons. First, the venerable 'Rover V8' is in whatever form a cast off 1950's Buick Engine. It really is not that complex, even in hugely tuned formats, and MS1 is vastly superior to what many think. MS2 is more expensive, far more complicated and to be honest debatable as to if you will gain much if anything vs MS1. Tuning and setup is everything, too many people think 'bigger is better' when 'small and beautifully set up properly' will leave them standing.
We like MS1, you can run NOS, even Traction Control if you want to, but for most its a good way to LEARN about the system, you can always upgrade the CPU in the ECU to MS2 if you really want to, and MS3 ?, State of the art, hugely complex, mouth wateringly superb, somewhat wasted on a 60+ year old wedge head Rover V8, and thats why we like MS1. Simple, affordable, easy to get to grips with and learn, relaible, robust and does exactly what it says on the tin - and then some.