When you think of Elise you see a mage who has 3 damage spells, correct? Q in both Spider and Human form and W in Human form are her ONLY 3 damaging spells that scale off of AP, which is reasonable because it's the same for pretty much every other mage in existence except for mordekaiser.
Now AD champions aren't quite set up like that, take Olaf for example - he has 1 skill that scales off of AD, Fiora has two. Ashe has 1. Caitlyn has 2. They aren't mages, they autoattack for a majority of their damage. (Tristana doesn't even HAVE spells that scale off of AD, Is she a mage like elise?)
Now Elise has a good 4 things that help her autoattack better. Her Q in spider form cost no mana and scales off of 8% of the targets missing HP and is a great short distance gap closer for your spiderlings.
Her W in spider form gives her incredible lane sustain and autoattack damage increasing her attack speed by a SHOCKING 140%, granted it's only 3 seconds.
Her E allows her to either stun an opponent, avoid aggro from the tower, escape into the jungle, initiate, or chase down a dying opponent. (Now that's a fun skill)
Her R allows her to turn into a spider, although she foregoes the benefit of extra "on hit" damage that mage elise's would enjoy, the free 25 MR and armor are still there along with the extra 200 DPS, not to mention her spiderlings benefit from Armor Pen make up for it completely.
It's not a troll build, no more than AD Tristana at the very least.