I'm not too pleased with abandoned/discontinued addons either, but that is par for the course since XF 1.0 first started featuring addons. And I can say that abandoned/discontinued addons were much more prevalent for us in 1.x than they've been in 2.x. In that case, some developers were well-intentioned but a bit wet behind the ears, and some of them apparently evaporated from the face of the earth.
And as you know, it's a hard adjustment when support disappears, and a new forum version comes along that breaks the addon that was deeply entrenched into the forum.
I've minimized my addons now to just a handful of long-established developers and where something has been discontinued, I've found replacements for most, and the remaining one or two I can probably modify the template modifications myself so they continue to work until another developer creates a replacement. I've long held off on a 2.2 upgrade since there is still fallout from a few such addons and developer issues, but I'm getting things in order to just launch as-is and be done with it.
I am still using a theme that is on shaky ground for this upgrade, but am going to have a replacement waiting in the wings for when they eventually pull the plug (which they will at some point in the near future I'm sure). My goal now is to launch with what I have currently, and make adjustments as things happen.