There are several reasons why a trust is useful to the developer.
First, the voting rights for the underlying owned property generally remain in the trust. This is probably less important to DVC, because the main reason this matters is electing the Board of Directors, and DVC already serves as the "authorized voting representative" for all units in those elections. But, there could be other less-common situations. For example, one of the timeshares I own is considering a vote to terminate the condominium plan--it's a long story and a very unusual situation. But, still, it happens. The DVC organizing documents do list a few situations that require a vote of the membership at large, and points conveyed to the trust would be voted by DVD, not individual owners.
The second reason is that generally the trust interests sold to buyers are not deeded. This makes recovering a non-performing ownership much easier. With a deeded interest, an owner who isn't paying their fees has to be foreclosed upon--a time-consuming action even if it is non-judicial (which Florida allows, but
the owner can object to and force a judicial foreclosure). With most trust products, termination is much simpler.
A trust allows the developer to repackage less popular resorts under the umbrella of the system-at-large, which usually is a better value proposition for the prospective buyer---which means you can charge more for it. It's also easier for a good sales agent to target their sales pitch to the resort(s) that are most compelling to the buyer, and emphasize that the buyer is getting access to those resorts.
All of those are potentially even simpler explanations than "RCID/CFTOD shenanigans." In other words, there is a reason that Marriott, Wyndham, etc. have all gone down this road despite the fact that none of them are under the RCID/CFTOD thumb.