I can't imagine regretting not doing Ultra. If it’s a great idea, I can maybe use it as a jumping off point for a story, without risking disqualification
Each to their own, but the extra challenge is the part I like about ULTRA, no matter how limiting it can be.
Everyone keeps coming back to the competition for their own reasons; some want to hang out with their friends, some want to show off their craft and make genuinely sublime film in 48 hours and some, like me, enjoy the creativity aspect over all else.
I like ULTRA because it can be super limiting, but forces everyone involved to push their creative limits - in my mind ULTRA should try to stop veteran teams making 'safe' films. This is often to the detriment of the finished product, and may give those not doing ULTRA a significant advantage, but that's a trade off I'm ok with.
I can understand that those teams who want to flex their craft and make objectively good film that ULTRA in the past has been unnecessarily constricting and worsened the final product, which is where I think you are coming from, but I know that my team were an instant and unanimous yes to the extra challenge for the reasons above.
Oh and there should definitely be an ULTRA award for best use of ULTRA, not best film that happens to be an ULTRA.