Most settings (alt-o - whatever) cannot be addressed with commands, and to keep the language manageable might not be the only reason for this fact.
There are a lot pro's and con's for adding more switches/commands... and enabling/disabling ballons for some events with a scripted command is no security-relevant issue, without doubt.
In addition to this, I think there should be an identifier for every setting that can be changed with a command, for complementary reasons (and for the very most, there is one).
However: scripts, as I understand them, are meant to complement and enrich the main program, not to sway that program, or settings made by it's users... (that's only my personal opinion).
For your own purposes, you might use a "sendkeys" alias or alter the values of mirc.ini directly - you can find several examples for these methods on this board.