Re: easy mode-line manipulation

[Richard Stallman]

    All in all, is a matter of how easy/deep we want the configuration of
    the mode-line be, and how much complication it costs. If the current
    model is deemed enough, then yes, a few more variables (notably one at
    the end, after the current column-number spec) would help.

I think it is enough.  You can always imagine ways to add levels
of power and complexity, but if we did them all, the result
would be impossibly complex and we wouldn't have time to do them.
I think it is better not to complicate this area any further.