I think there are really only two reasons to buy direct in the near future:
1) You really love Riviera and want to stay there - Assuming that you don't already own a contract that would let you stay at Riviera, there's no other way to be able to stay at the resort.
2) You're looking at one of the higher priced resale resorts - If you're looking at the Polynesian (average price $154 per point) or the Grand Floridian (average price $165 per point), then it's not really a big jump to the direct price for Riviera. It's a $30 to $40 per point jump before any incentives. The eventual return of some kind of perks could cover that difference.
Longer term, there may be an issue after 2042 for availability at the remaining original resorts. Once Beach Club, Boardwalk, Boulder Ridge, Hilton Head, a majority of Old Key West and Vero Beach all expire, the number of resorts where restricted members can use their points shrinks and that may make it more difficult to stay outside your home resort (if that is important to you). It's a ways off, but it's something to consider if you're younger.