“Lead on, Macduff” – the original seems to be “LAY on, Macduff”, as in “Go ahead, attack me with your sword, I am immortal, mwahahaha!”
Rephrasing “Methinks the lady doth protest too much” makes sense, since it’s a convenient way of conveying the concept of someone protesting a lot implying they might be guilty, but why “Lead on, Macfuff” when you mean “after you”?
This doesn’t really speak to the OP, but all this Shakespeare-mangling talk reminds me of an over-the-top breastfeeding advocate who used to sign-off her correspondence with:
I have given suck, and know How tender 'tis to love the babe that milks me
I always wanted to ask her, “Did you read the next couple of lines, dipshit?”
Much like “sweets to the sweet.” Um, those are funeral flowers, not a box of choccies for your sweetie pie.
Or “sea change.” You have to drown first.
Or “the play’s the thing.” Wherein you’ll catch the conscience of the king? (ST:TOS, innovatively, used the second half of the couplet as an episode title.)
Sorry, I really have no problem with overused quotes, cliches or whatever. If used in the right time and place sometimes even the most annoying quotes can be hilarious. So if you have to put up with some other irritating moments to get to one of those perfect moments, well C’est la vie.