I think spine is an attractive tool, I'm considering buying the Pro version. However the big deal breaker is the lack of a particle system, as of now Spine users have to animate each particle by hand instead of just adding an emitter that spawns them. I have read the forum and seen that Nate have said that there will be no particle system due to the maintenance debt that would come with it - namely supporting every different runtime that handles particles differently.
I can understand that, HOWEVER..... I think you can dodge that debt entirely by labeling the feature "Experimental", adding a warning dialogue box that explains that particles only work within Spine, and are not supported for export. This would not incur any runtime maintenance debt, and would be a huge timesaver for users who want to use particles in Spine.
In fact there are a few of us who want to use spine primarily as a stand alone tool, not for exporting to game engines. Many people out there are looking for easy and cheap ways of making animations for video, twitch, youtube, websites etc. And right now people like us are forced to hand-animate every single particle instead of just adding an emitter that farts out a bunch of particles in a specific direction with a specific transform and lifetime... It seems like you already have 90% of the features needed for a particle system, the last 10% would greatly help users, and also expand your user base beyond those who use spine as a gamedev tool.
I am now weighing between using Spine or After Effects, and I would frankly rather support spine than to rent AE from Adobe.
Can we get a particle system please?