Rational: Or maybe it’s Begged Ish because no woman wear it, not because they’re not allowed. There’s no Issur on men to wear heels (Mitzad the heels themselves). But it’s Begged Ishah because only women wear them. So too by a Tallis.
Don’t give me a random rule and a Rambam and tell me it’s a big deal to go against them. The Mechaber knew the Rambam too and Paskened against him. Look at the Mechaber and look at the Tosfos I cited for the reason why.