I think the knowledge base has improved enormously, simply being able to get to the states easily has changed things massively. In '74 I could have imagined going to the moon as easily as going to the USA.
As Patto points out, most are middle aged now, with 30 + years of experience, there is the internet etc. And not all dj's actually knew as much as we thought they did back then - they just had better records than most of us!
Even in the last 10 or so years since I stopped collecting so many things have turned up - exotic foreign copies thanks to fans overseas (ex pats or otherwise) and the internet to easily share that info. We now have some of our 'heroes' (as in artists/producers) even contributing to this site, who could have predicted that?
And, though it might be a predominantly ovo scene, compilations and as a result, all of those previously unissued recordings made available for reasonable money.
In fact you would have to say all this extra knowledge must have made the scene a much, much better place. thanks to a thread on here I saw my first 'issue' of the Volcano's "You're number 1" today. When I had my demo it was reckoned never to have been issued at all - so there's an example.
Unfortunately, as Toad says, the majority of people just want to hear what they were listening to when they were teenagers and first on the scene, so how much benefit has all this additional knowledge and development really been to the majority?
I think ID's "98% wanted to listen or dance" point probably is still quite near the mark.