I think there are different ways to look at MB. Personally, if I don't need the points for the current UY, selling the back for $20/point is a very quick and easy way to monetize your points. And, the $20 is coming off the upfront cost to purchase, not spread out over the life of the contract, so that makes it even more valuable.
But, it sort of really comes down to whether you need/want the points to use or not and, if so, how you'd want to use those points. If you want to use that first year's points for a room that's already booked up using a "welcome home" stay, well, you're going to get pretty good value from those points. OTOH, if you already have your stays for the upcoming 7+ months booked, you don't really need those extra 150 points right now, a $20/point discount is pretty nice. Or, if you're somewhere in the middle - say, you just need 24 or so extra points within the 7-month window, well, you can get those pretty cheap with the BOGO OTUPs through MMB. You can also compare it to resale contracts - if you bought a contract that didn't have current UY points, but had full points for the next UY, would the asking price be $20/point cheaper? In most cases, probably not, although there high be some negotiation on current year dues depending on when you purchase.
And, MB is even more valuable IMO the closer you are to the end of your UY. If you had a February UY and were planning on buying right now, chance are you don't really need your 2025 UY points and you get a whole year's worth of points for $20/point without having to pay dues on those points. So, that's an even bigger benefit.
