If you mean the non-evaluation during parsing should be a switch then I disagree. It would be very clumsy since, unlike with identifiers, commands' parameters are determined after evaluation of the line. So a call to timer currently could exist as /timer -h $moo $blah $somethingelse. Now if the non-evaluation of the <command> parameter of mIRC were implemented then how would mIRC know what it should or should not identify? $moo could evaluate to a single number and so could $blah, meaning $somethingelse shouldn't be evaluated, or $blah could evaluate to two numbers meaning both $blah and $somethingelse should remain as-is. Hundreds of other variations are possible and there's simply no good way for mIRC to know how to behave.
In other words, for commands to have parameters that remain unevaluated it needs to apply to the whole of the line. Which means it should be something like a directive or a command prefix as qwerty said.
