I'd say it's the other way 'round: the problem of the invisible multiplication operator is that it precludes multi-character symbols. (I think Dijkstra wrote about that.)

Yup, and he was absolutely right. I've adopted multicharacter names (though usually abbreviations or short ones) for my day to day calculations, and a visible multiplication.

Mind you, if I get deep into integration and the only reflexes from my Jackson days kick back in, the notation reverts entirely. At some point it magically switches back after the act of integration is done, though.