Out of curiosity, how much of that do you feel is due to Riftmaker's design, and how much do you think that might be due to the general lack of items like Riftmaker in the past causing champion design to skew away from spaces Riftmaker might appeal to?
Looking at AD vs. AP bruisers, most AP bruiser-types (Gragas, Rumble, Sylas, Diana, Cho'Gath, Swain) tend to end up favoring burstier builds or solid tank builds, and my opinion for a while has been that the inflexibility of AP as a stat (compared to AD, which can be better focused on a specific role due to the additional tuning levers it has) has kind of limited the ability to design AP bruisers who aren't encouraged to go heavily tank or heavily AP. I think this, in turn, limits the appeal of longer-duration sustain bruiser items, because there aren't enough characters that have the pattern innately to want to buy an item that enhances it. Riftmaker on its own is an item that enhances the pattern if...