At SSR, THVs have the same point costs as SSR's two-bedroom villas. However, they are not equivalent in terms of rack rates.
Yes they are. Plug any set of dates into the booking engine at waltdisneyworld.com. Assuming that a Treehouse Villa is available, the prices for 2B and Treehouse accommodations are identical.
As previously stated, you can attempt to book a Treehouse on cash for many dates and find no inventory available. I tried many dates particularly in June, July and August and was offered a 2B at SSR but no Treehouse.
It's worth noting that Treehouses are excluded from promotional offers available to the general public. The fine print of the offers states that the Discount for "Deluxe Villa Accommodations" applies only to Studio, One Bedroom and Two Bedroom villas. I went so far as to confirm that the Treehouses are excluded. In my trials, there were dates where I was offered a Treehouse without any discount codes but was unable to book the same dates with the code.
If you want to believe that there are already 30 cash Treehouses booked for dates in June, July and August at full rack rates, then we'll just have to agree to disagree on that point.
As for the question of why DVC would make more than 30 Treehouses available to members, I would propose that it may simply be because DVC is not as diabolical as some would portray them to be.
Historically DVC has excluded BoardWalk View villas from any cash inventory. They aren't contractually obligated to exclude these villas from CRO bookings--they simply do it because they know members have a higher preference for the BW View than the Pool View. Similarly non members cannot pay cash for the "near Hospitality House" villas at OKW.
DVC has always had first crack at resort availability to pull out units freed-up by member trades, undeclared units, points held by DVC and so on. Yet there have never been any obvious signs that DVC is pulling an inordinately high number of units with a superior view or during periods when demand is higher.
Just because DVC COULD hold onto 30 Treehouse villas every night of the does not mean that they are. Based upon my own trials on the Disney reservation site and relative apathy toward them among the non-DVC community, I highly doubt DVC has chosen that approach. YMMV.