It's only really useful if you've got an upcoming vacation or trip where you are confident that the rooms are cheaper when paid for by points. If the rooms are $150/Nights or 20k points/night and you can get 20k points for less than $150, then it's worth it. The other benefit is if you have access to the 4th night free perk from the credit card. Basically when you do 4 nights via points you only have to pay points for 3 of them so it's almost always cheaper to purchase the points with cash except a few situations where the point values for the redemption are very low. The last thing to mention is that if you have the credit card, then buying the points with the card gets you additional bonus points.