There is some evidence that things are changing in our favor and that the bike is in fact increasing in popularity, but from a buisiness point of view the fact is that the TW isn't yet in high demand at all relative to most bikes in this displacement class.
They come in pairs, two to a crate and dealers are hesitant to replenish annual stock on a slow moving model. When they run out, they gotta order TWO more, not just yours. They're far more likely to sell 4, 6, 8 or even 10 XT's or little Hondas than they are to sell 4 Tw's in a year, and they assess their risks and do their ordering accordingly.
The other option is for them to get yours by doing an inventory swap with another dealer who happens to have one in stock. Not a lot in it for the dealer on either end, but sometimes a win/win.
Historically, in vast areas of the market TW's have tended to languish in showrooms only to be blown out at a loss down the road. When folks begin to insist on getting what they wanted, then walk out if it is not offered rather than allowing themselves to be steered to that XT or 230 instead, real demand will be established and stocking levels will increase.