AD be like: What was that? Did you just hit me for half my hp and burned off a combo? Too bad you didn't waste money on a tear, I've already healed my hp back with just two auto attacks on minions. I don't need to worry about itemization when it comes to building one item to give me full CDR for building straight damage and making practically no sacrifices for such a high CDR. It isn't our fault that most of our ADC's like Vayne are dashing around every 2.9 seconds with high mobility and extreme dps while also having higher survivability stats than most mages.
AP be like: Wow I just got hit twice and half my hp is gone! I better go back to base before one of them uses their ult and kills me right away. I had to burn off half of my mana bar just to prevent them from pushing my tower. I better not pick any mage that is considered a poke mage because they are prety much worthless now, considering AD's can just hit a minion or two to get their hp back. Why don't we get the amazing sustain that they get? And why in the hell do they get free CDR when we are the casters that actually use spells to fight? Isn't there suppose to be a window of opportunity, like with our spells? I don't see one when they have an attack speed of 1.96 with 70% crit full CDR and more HP than I have.