I love seeing more excellent tooling made with bash/shell scripts. For situations like this one, where all the underlying heavy lifting is done with other CLI utilities, shellscript is the perfect fit.
That's not to say the above doesn't happen with other languages/systems. It most certainly does. It just seems to happen faster in shell (especially when people start getting adventuresome in their use of fancy shell features).
Why not use the preferred tool?
Otherwise, why not write it in dash for strict POSIX conformance?
I do admit that there are some profound bash applications that are important to me, principally rear.