Hmmm...well, they could bundle the adaptor with the system... Too little, too late, though. Still, Sony managed to sell almost 2-3 million of their adaptors before it was sold in bundles. The reason, as I have stated previously, is that Sony pushed the peripheral with games (produced by them and others) and marketed it. If it weren't for Sony's own SOCOM and SOCOM II, it would not have done nearly as well.
That's really what I'm talking about...the first party has to lead the way with their peripherals by providing people with a reason to use it...then 3rd parties can see the real worth in spending more money to support it as well. Then there are the compensations by MS and Sony for producing online-enabled titles. I just can't see how this is not the root of the problem (lack of marketing/software for the hardware). Lack of hardware units being out there is directly tied to the lack of software/marketing support by the maker. Bundling alone isn't going do it, IMO. Certainly, I don't think it's the whole, 'If you build it, they will come' thing...you have to build it, then support, and then, maybe, they'll come.