The mystery seems to be as to why the younger, presumably 'fresher' producers are making largely dull d 'n b...
Nice ideas on this but you missed a few things I think...
Renegade technology vs. 'officially sanctioned'. In the period 1991-1996, equipment manufacturers weren't aware of dance music producers as a seperate market, and they didn't make kit especially for them - so dance producers had to put some thought into how to get the sounds they wanted from the machines built for the general market. Plus it was expensive, so they had to save and they generally didn't have too much (a sampler, and few keyboards and a DAT was a typical setup for dance music pre-1997ish).
Around 1997 manufacturers cottoned on to this big market of amateur/bedroom producers and started to make groovebox-type products that laid it all out for you, and the move to software music made studio building a lot cheaper. Result is that where producers used to be techno-rebels, they are now techno-consumers - acquiring kit that is perfectly attuned to thier apparent desires, with little financial or emotional outlay.
I have mixed feelings on this. I think this blurring of the boundaries between producers and audience in dance music is probably unstoppable, and I like the 100% access to the means of production that software music allows, cos I remember trying to save up for an Akai S950 when I was 17. But making electronic music is always about an engagement with the technology, and if the machines are gratifying your every whim without you even thinking about it, you never learn how be the master in that process. For me, making music on the purpose-designed equipment is like the 'officially sanctioned' graffiti you see around - always slightly crap compared to the real thing, because the factor of negotiation with a hostile enviroment isn't there. The smarter producers realise this and come up with stategies to get round it, like Burial using Soundforge (which is an audio editing program - you're not supposed to make tunes on it). But obviously most people go down the path of least resistance. I guess this might be psychological too - because punk ideas about questioning your environment were still current in the early days of dance music, where as todays kids live in a more narrowly defined, results-driven world. Maybe I'm judging them too harshly though.
Also, the big innovative strides always seem to occur when the music moves away from the clubs. If dance music is made for dancing, form will always be driven by function - and club/dance styles often reach a zenith of pure functionality that allow the individual producer very little room to manouver, and make it extremely dull for the listener (as opposed to the dancer) - loads of examples of this, trance, progressive house, etc. Where there is innovation, it's about making the music more boldly functional, like what Chicago house did to disco.
However when the medium of delivery moves away from clubs towards something else, like mixtapes (hardcore 91-94), pirate radio (jungle 92-95, post-garage sounds 01-06) or the net (IDM/Clicks and cuts) - suddenly producers get loads more space to play around with ideas, because they don't have to be rocking bodies with every track. It helps that non-club scenes are often marginalised in some way - it means they're smaller and have something of a siege mentality, so it's easier for producers to swap ideas.
The key era is when a new sound emerges back into the clubs - what D&B went through in '95-97 and never really got right, and what dubstep is doing now.