thanks for your question, and sorry for the late answer. As I was on vacation, I didn't have a chance to reply earlier.
Such an option already exists, namely a plugin filter hook, as described in my first reply in this thread :-)
I will not add a checkbox for this though, as that would not be useful and would just confuse regular users.
And I agree that reducing HTTP requests is a good thing, and as TablePress uses the WordPress script/style enqueuing functionality, this can easily be used by a minification plugin that combines all CSS file into one.