You can try putting forwards your arguments for a different -- presumably better in your eyes -- way of working; but given how long the current mechanism has been in place; that the mechanism is -- has to be -- deeply embedded within the Perl core; and the historic convention that says Perl does not break backward compatibility; and the net result is that you will have to learn to live with what is; because it is very unlikely to change at this point in time.
Forgot to reply to that bit. I already outlined what I (probably arrogantly) believe would be a better solution in the middle of this page:
But sadly, I think you are probably right that we are stuck with the current taint mode implementation. I'm just surprised that it wasn't done that way in the first place.