I've talked about Marriott travel packages before, and for me that's where I get value from buying points.
For example, last year I transferred 60,000 UR points to Marriott to have enough for a Marriott travel package that I redeemed for SW miles and a Cat 6 property. I could (should!!!) have bought SPG points to transfer over and it would have only cost me $455 for 20K Starpoints = 60K Marriott points. Instead I gave up 60K UR points worth at least $600 cash or $900 thru the CSR UR portal.
So determined not to make that mistake again, I bought Starpoints on sale last year for both DH and me for another Marriott travel package, cost me $1365 for 60K Starpoints = 180K Marriott points...with no concrete plan for them. (Went thru points . com and put it on my SPG AX to max out what I could receive for my spend.)
I searched for Marriott places where I'd want to spend a week, and decided on a Marriott in Costa Rica over Thanksgiving break which costs $2400 OOP or 240K Marriott points. I've booked that reward stay even though I don't have enough Marriott points in my account yet. Marriott lets you do this, which is awesome. I plan on redeeming for 120K SW miles as the miles part of that travel package and that's worth $1700 to me (actually more than $1700 since I have a SW CP [which I got from my travel package redemption last year - RIP hotel transfers counting toward CP

]). So for $1365 in points purchased, I'm getting at least $4100 in value. Granted, between DH and me, we have other URs and MRs to transfer the remaining 180K over to Marriott to redeem for a 360,000 Marriott travel package, so at this point I don't NEED to buy Starpoints...but I probably will. Because 1) it will help me reach my SPG Biz MSR, and 2) even if I spend another $1365 on points and use those for this redemption, the combined total of $2730 OOP is less than the value ($4100) I'm extracting out of the points.
FWIW, I think the ability to reserve award space without having the points in your account is a huge under-reported benefit with Marriott.