The sponsorship system can be risky. Disney wants a commitment of a lot of money and for a set period of time. I don't know what their average request is but it seems like they try to get 10-year contracts based off of other attraction sponsorships. Financially it has to make sense for the sponsor (will this attraction really make guests more eager to use our service?) and it has to make sense for Disney where they have enough creative control while also paying enough desired for R&D, building and maintenance.
Sometimes I think about what SeaVenture/Maelstrom could have been. While it's not easy to find much, WED wanted to create a journey less about the real-world and more about folklore, not just with trolls, but following the rainbow bridge to Valhalla, with a score composed by the Sherman Brothers (btw, if anyone has any extra info or clips of this music tucked away somewhere, please please share!) Maelstrom was wonderful, and of course Imagineers needed to make adjustments to make the sponsors happy, but honestly the original pitch sounds much more exciting to me. Would Disney have maintained this after sponsors choosing not to renew? I'm not sure, but I sometimes wonder if this could have been a next-generation of Pirates of the Caribbean.
Ultimately Disney needs to be prepared to maintain anything that they build, IMHO. Letting stuff fall apart in the parks is ultimately their decision, and these are things that they should at least keep in mind while designing and building. Sadly this seems to be manifesting in less original ideas, less AAs and more screens.