The other reasons are probably more personal. The initial tmux learning curve is steep, but once you've got it, it rewards you with a super fast workflow that suits you. I know this sounds extremely stupid, but the "hacker cred" is large with tmux. I got hooked on tmux by a coworker who used it and ruled. I've never seen that with terminator, although it should be equally possible.
[0] https://news.ycombinator.com/item?id=13338592#13341184 https://news.ycombinator.com/item?id=13342341#13348007 https://news.ycombinator.com/item?id=11995816#11998921
Tmux's competition is not terminator, but screen.
I understand term* provides some additional functions, but would you still consider it worthwhile?
I've had some problem applying this principle when using tmux locally on a system with i3. You kinda need to be consistent in which of the 2 you use to create new shell windows.
I am now trying to simplify my workflow by only using tmux and emacs. It's minimal and works on almost any system I log into.
I use spacemacs and coming from vim, its taking some getting used to but I'm still always trying to do more things in emacs and not switch to my terminal workspace.
I feel spacemacs is just a vim clone with really bad cpu and ram utilization. If I am going that road, why not use an ide like eclipse or visual studio instead?