the grooves are for brake, front, and Campag ergo lever shift cables, rear..

fill the grooves up with extra bits of brake cable housing if you wish,
before you wrap the bars.

The short ramp is compensated for modern Brifters being so long.

there are dummy brake levers for stokers handlebars to put opposite
your sole brake lever, but whats wrong with a rear brake, too
they come in pairs you know.

I don't tend to ride long in the drops, but you know, YMMV.