Here's Tiff about the ST185 and the MR2:
And Clarkson destroying the ST202 in a bit about coupes:
And then about the GT4:
So, the gen 6 was:
too ugly; and,
too expensive.
But that first video is really making me want to get a 5.
By your logic the MR2 should've been a bit of a sales success, which I don't think it was. Toyota used to put its most powerful engines in its coupes, the 3S-GTE and 7M-GTE, 1JZ-GTE. That changed with the 7.
Coupes may be a bit of a fashion item, but so are the Fiat 500. Ironically I think the 500 Abarth is quite desirable.
The fact is though that the lower powered versions will always outsell the higher powered ones, simply as most people want a good looking car but the best fuel economy, or simply the lowest cost car. And of course, when Toyota made a superb handling coupe with a low power engine that's very usable, what do people do? Complain about a lack of power!
Looking at the US sales for the Scion FR-S (which is what the GT86 is sold as in the States), we get the following sales figures:
Scion
FR-S
2016
7.457
2015
10.507
2014
14.062
2013
18.327
2012
11.417
Looks like it sold worse than the gen 6!
I think at the moment only Audi are making a decent coupe in the TT.