I will try to field this question.
1. Cost.
2. The ability to control both fuel & timing.
3. The ease of install & tuning using any computer that has windows.
4. Ability to datalog.
5. The ability to upgrade. Yes there are many different options with the mpi tuner. Such as EBC, Extra Injectors, Setting Rev Limiter, Removing Govener (i know protege's don't have it), etc.
6. Ability to add nitrous.
7. Can have 2 maps (daily & Race).
8. Ability to adjust for high altitudes, warm & cold weather.
Just to name a few.
Chas