The NSX is deemed an 'important' car because it changed the face of supercars, it forced Ferrari to go back to the drawing board. There were a number of production firsts, and there is romanticism surrounding the fact it was built without compromise and not to a cost (up to a point!). Honda for example built a factory solely for the NSX, where it was largely hand built. Perhaps most importantly of all, the late, great Ayrton Senna was associated with the car's development. Gordan Murray also benchmarked the McLaren F1 against the NSX.
People often bemoan about the car's lack of power, but back in the day, nigh on 300bhp was the norm. Honda couldn't really afford to create a new engine for it later in the car's lifespan, and besides, they felt that power wasn't the most important element. The JDM market got the NSX-R, which BMI and YouTube videos will show you was comparable to the very latest supercars. Most importantly, it is a great drivers car, period.
I agree they look a bit dated, but i still love the look of the facelift car even in standard form. I appreciate the retroness of an early NSX-R too.
As said above, it became a cult car again with the advent of Gran Turismo. I think we'd all agree it was the best handling car in the game!