No, that is not practical, since !sometext is more likely to be plain text than something that needs to be evaluated. That is why mIRC specifically applies ! only to $identifiers and %variables in the if statement.
And there is a difference between adding a new identifier or feature, which may possibly require some users to change their scripts, and breaking a core aspect of how an if statement works, which will likely break large numbers of scripts for everyone.
In fact, v6.34 was released specifically to address a minor change to the "if" statement that had wide repercussions that were not noticed until after the release of v6.33.
It is important to make sure that basic, core scripting behaviours are consistent and reliable across versions and I make significant effort to make sure that is the case.
