The point is being non turbo / supercharged, it's attractive to P platers. I mean, it's not like we ever see P platers in Honda Type Rs, 350Z, S2000 or non-turbo Supras.
But you're not going to want to slide it daily in traffic either.
On the contrary, most of the P platers I see are still getting around in turbocharged, supercharged, or V8 vehicles. Either the laws aren't upheld, or they're full of holes that are easily exploited.
For sensible drivers, yes, but we know there are a lot of less than sensible drivers on the road - cue some P plate drivers and other hooligans.
Sliding aside, it's also the thought of having to keep it on the boil at 5,000rpm+ if you want to plug a hole in the traffic, if you want to merge before your lane ends, if you need to run away from the bad guys etc.
There are 1000's of different cars that must worry about plugging a hole in traffic or merging before the end of the lanes before a FT86 has too. Dropping from 4th to 3rd is a way to get revs if need be and that's been going on for 80+ years. I think 86 owners will work out how to do that.