I have Chewie in 6 stars and I am the only one using him in top 10 of my server. Chewie acts as a health reserve for my team and he is rarely killed in his taunted turn. That being said, Chewie works seamlessly with barriss who also has many hp because their health can be equalized to all your glass cannons when needed. The typical scenario in arena is that the opponents severely injured -if not dead already- your glass cannons in the first turn, then chewie taunts, barriss equalizes, chewie self heals. Then you have undergone the hardest part of the match.
However, if you don't have barriss, I won't hesitate a second to swap Chewie out.