TT is currently a very unbalanced and frustrating game mode. All of the problems SR faces are multiplied tenfold on 3v3, since its basically a faster, more snowbally version of SR. Teamwork is paramount in order to win, which can make grouping with randoms incredibly frustrating.
Carrying on 3v3 is harder since split-pushing is so easily countered, and the team that falls behind (which is incredibly easy in the first 5-10 minutes of the game) has no options other than to turtle at their base and hope the enemy team makes a mistake. Also, support comps can only be countered by other support comps, which is mostly unlikely when queuing up solo. Most teams will always want to surrender in the first 10-15 minutes, regardless of either team composition. As soon as things go bad, most players will just give up, and most of the time they're going to be on your team (again, unless you're playing with people you know).
You pretty much have to play with friends in order to enjoy 3v3. The only reason I still occasionally play it is because I'm a bit of a masochist and there's nothing else to play outside of the RGM. However, if a Crystal Scar map became permanent then I would leave 3v3 in a heartbeat.