In addition to the cheap points, there also is the float by effectively using a credit card to pay mortgage. That's something for me. Of course that requires being able to find reloads timely. If buying them 30 days in advance, obviously that's out the window.
I kind of think if the haul here is 6x Hilton at $3.95 per 3000 it's pretty good, but not worth going crazy. To me, the key value is meeting spending bonuses with mortgage payments. For example, I am working toward the 15k bonus on my Amex gold. Getting across the finish line by paying mortgage frees up the spend I would have had to put on the gold card for other bonuses.
For example, someone with 40k a year in bills that can't otherwise be paid with a cc, one option might be the Hilton Honors reserve. For $316 (plus the annual fee), you get 120,000 HH points, diamond status, and a free weekend night. Or, for 25k in spend on a US Airways card, you pay $197.50 for 25k US miles and 10k are EQM. Depending how one values status, such things might be worth more than 6x hh points.