A rx7 lapped Tsukuba at 1:06.35 and the supra 1:06:75. We modify our cars to be better because we can't afford lambos or Ferraris. I don't think anyone wants a stock supra so that point doesn't mean anything. You said the supra is good when it is modified. The record was eventually broken by the Porsche Carrera GT. 2 the mk4 supra had a brake distance record for production cars from 70 to 0 in 149 feet beating supercars like the McLaren f1 and Bugatti eb110. Coming from the drift King himself, that has to say something. Keiichi Tsuchiya once said the mk4 Supra has a great chassis. And potentially, cool some of the heat on the Mk4 Supra down. It would bring happiness to most of the car community. I though, would really want the Mk5 Supra to succeed. That's my problem with it, people tend to see these Supras as goddesses and so on, and yet they don't think about other 's degree of overrated-ness( if there is such a word) is sheer madness!
I myself, unlike most people, think the Supra is a GT car. The NSX too was super attractive, the ARTA NSX even broke the Tsukuba lap record, showing that Supras aren't the only great GT race car in the 90s Japanese era. You might argue that the Supra dominated the early JGTC (The Japanese GT series), but let's not forget, when Nissan took over with the R34 GT-R, it too dominated the series. It brought to most of our minds that - a Supra is a car for drag racing, it's very powerful and capable.
The reason behind all the fame of the Supra, I think, is because of the Fast and Furious franchise. The Mazda is capable of lapping Tsukuba, stock, in the 1:04 barrier, which was unheard of back in the days. The RX-7 however has a 13B twin turbo engine, which is like nothing else. I get it, so what about the RX-7, a car that is front-engined, rear-drive, like the Supra, costs just about the same as the Supra. You might say 'But the NSX is much more expensive than the Supra though'. The NSX for example, has a C30B/C32B engine that is made from the ground up to scare the world, and show the world that it's capable of doing great things. The competition however, is much more attractive. I myself don't find it attractive at all. Being the flagship sportscar of a firm, I would assume that Toyota would develop an engine from ground up, not just grab whatever in the firm's parts bin to put it in the engine.
Hell you can even grab one of the 2JZ engines from a Toyota Aristo, which is sort of like the Japanese version of the Lexus GS300. Even if the engine is, the car still won't be that great because of an engine. The problem here is that stock, they aren't great. I often see them go for 1000bhp easily without much major modifications. I do freely admit, that the Supra's 2JZ is extremely capable. But the Supra when tuned is extremely fast.