I do all emissaries, but that is more for the rep so i can get to paragon chests faster and get my mounts. Invasions...not sure if those bosses mean crap...and honestly, Argus bosses give something good, at least they did before I hit 75 artifact level on 2 specs and needed AP...for those who need AP for a spec, why not? Also, with the robot that lets you solo any boss, why not?
I also do the Argus bosses so I can get shards for the weekly quest for my 300 items that help me play the trinket lottery with our RNG loot guy...still hoping for a 910 crystal...probably will happen last week of Legion lol