I don't script any on input event myself so I won't use any of these, this is just for consistency.

There's no point saying "not really" because you "can't really think of any other time ...", that's saying you don't see why the OP suggested this in the first place.

It is much more important to have a "safe" way of knowing which characters can be used as a command prefix than having a new identifier that just save bytes, even if this new identifier handle 99% of cases that would require $cmdprefix.

What if I want to count how many command I typed, regardless of $ctrlenter or $inpaste ? This is just one exemple, part of the 1%..