[whpalmer4]

I doubt very much they are trying to deprecate single-action lists (or bucket lists as you termed them). That doesn't mean that every single spot in the program necessarily works as well with a single-action list as it does with a parallel or sequential project, and this would seem to be one of those spots. The preference in question controls whether projects and action groups are parallel or sequential in nature, and there is no such animal as a "bucket list" for action groups, so accommodating you would require another preference setting at the least. File your request with Help->Send Feedback to have it officially tracked....

There's stuff above that section dealing with single-action lists, so I find the evidence that they are deprecating single-action lists is hard to see. I'd guess no one thought it was worth the trouble to make a single-action list a default project type, given the annoyance of having to provide another UI element, and the expectation that most people are going to be making regular projects the bulk of the time.