Spec racing is where 95% of racers purchase one of each 'spec' component in order to have fun on a budget and participate in tight racing. It's also where 5% of racers exploit the class by purchasing many of each 'spec' component in hopes of finding a silver bullet for the competition. Ironically, the 5% are usually veteran racers that should be participating in much faster classes but gain much satisfaction from their weekly stand on the podium. Translation - spec racing doesn't really exist in its intended form...just an illusion.
Not all spec is bad...
Spec tires - good
spec batteries - since lipo, mostly good
Spec bodies - not necessary if rules actually include body dimensions; if it conforms, it's legal (see ROAR, EFRA, GBS, etc)
spec motors - silly when done with the spec sticker and controlled distribution channel approach.
Unless we had "bluprinted" spec motors...but then they'd cost way more and defeat the purpose anyway.
Here's a little story about spec racing. dirtoval.com (DODC) uses spec motors and spec packs. At last year's US Open Wheel Champs, I went down there with the only DODC stickered 17.5 I had left (my supposed good one let the solder out in practice). In 17.5 EDM I qualified 2nd in round one to lock in to the show and TQ'ed round two. After my motor was torn down, I was told it was not too great. I saw some friends messing with a motor dyno and had them toss it on there just for fun. They laughed at the numbers. I had just TQ'ed a round with it, but by the numbers it was junk. I knew I needed another tenth to beat the guy who had TQ'ed round one, so I went and borrowed a known good motor. Popped it in, changed nothing else, and BOOM, there was my tenth. Ended up hot lapping the main and winning.
So, what I'm getting at with that story is...why were we doing spec again? They should all be pretty similar yet I did a heads up swap and picked up a solid tenth on dirt. How big of a gain would it have been if I was holding it open on a carpet track?
If motors were $5, sure, let's spec 'em out and we'll all buy 10. But playing the lottery at $80 a ticket (many times it's a lottery to find the best of the leftovers, if you know what I mean) is not fun.