It's not NA or not. It's the fact that the RCF is a big fat heavy 3850lb PIG and the engine doesn't make use of its powerband that well, as it has an odd tendency to slow down up top. I love NA V8s, both of my cars have giant lumps in the engine bay: a 5.0 Jag V8 and a 5.6L Infiniti VK56VD that makes close to 500HP crank with mods. The other parts where Lexus looks like a lameduck is its boring V6s. The same 3.5L mill that's been around for 10 years now with the same 300HP.
Also, compared to their competitors, the Lexus' 2.0T is utter trash. Slow, unresponsive trash that is considerably slower per metric across the board, compared to the BMW's N20 equipped cars that are super zippy.
I'm not denying that the RCF doesn't have other issues that keep it from being the first choice in the sport luxury sedan segment but I also think it deserves props for doing certain things well. If I was in the market for a car in that segment I would absolutely give it a serious look, especially if reliability and luxury were bigger requirements than outright performance.