I could see this being done well-- it's not hard to beat bash for syntax and functionality-- but I could also see it being done poorly or considered an ancillary feature.
Shell scripting sucks, but it's the only language I know that lets me write tiny little scripts in not minutes but seconds, inline, without breaking out of the flow. Just like dynamic versus static languages, the quantitative difference in writing speed is enough to make a qualitative difference in the types of programs that can be written; and the difference between a non-scriptable shell and a scriptable one is like the difference between a GUI and a good CLI.
A large part of that scriptability is just grep and sed and friends, which TermKit apparently does support, but sometimes bash's loop structures are also required...
Just my two cents.