Agree - all fair points, but the ECU was hard to reflash too, but the market was strong enough that Cobb did it. But it applied to all 335s sold. Here, we're dealing with time primarily (since they're slowly being traded to third owners), and market penetration (how many xi's sold north of like ... DC? I find cars in the US don't even have heated seats, much less AWD, hehe). But on top of that, drivers have to actually want that and want to pay - if I still had mine, I'd consider it a gimmick and want to give Cobb, say, 100 bucks for the novelty factor - but I wouldn't track with it, for instance, as I enjoy what AWD does for me for tracking.
Complicated issue, for sure, but one I'm afraid we'll see no resolution to.