(Do note that some points above have been fixed in 6.7.0)
As any open-source project or software company for that matter, we have a group of people that works on Flowable and it’s not unlimited ;-). As such, we need to make choices where we invest our time and effort. As you can see on the github repo, we’re very active on the engine side, but indeed less so on the Modeler side of things. One of the reasons is that (with the exception of I believe @DavidPLamas in the past), there’s not many contributions happening in this area. We’re currently evaluating what we want to do in the future here (as you know, it’ based on AngularJS …) and what that would be. Once that’s decided, we’ll of course communicate this to the community.