Emulating an HTTP session (with cookies passing) between request is more complicated for instance. Retry based on response content is doable but easier with a declarative format. jq is perfect for JSON response, what about HTML/XML response? Our testers prefer to write a text based declarative test, instead of a Bash script. It depends on your needs/backgrounds.
Using a binary can be (in my experience, 99% of the time) an enormous convenience and performance boost over including a whole runtime for those languages.
How can they claim 16h of work - I own an Asus m16 with the same CPU and a 90Wh battery and after some tweaking my Ubuntu drains 9.xWh without touching anything ... With Firefox open it already consumes 12wH - so I guess I can be happy if I can get 6h of work done with one load and this laptop here can't do much better...