I think we can blame the greenies for some of it, but when it comes to the higher performance cars, part of the blame lies with us within the motoring enthusiast community.
You see as we start competing on power output, 1/4 mile times, TLGP's, etc, all out performance starts becoming critical and things like engine noise, crisp throttle response from a NA engine and real exhaust notes all start taking a back seat to who crosses the line first. And sadly to cross the line first, the easiest route is forced induction...
Take the M3 CSL vs 1M as a classic example. The "purists" amongst us would agree which is the true M car. Reality is that many people would not spend R500k+ on a 1M, if a FWD GTI with chip + zorst can take you out at the lights. Take nothing away from the 1M - it's an amazing car and I'm just using it as an example to illustrate my point.