ADC isn't as strong as people make out. The ADC of the winning bot lane is strong. The issue is not that ADC items are too cheap, its that ADC items are too cheap as a % of the gold earned by the ADC that wins lane and too expensive as a % of the gold earned by the ADC that loses the lane. If bot lane was evened up then a lot of the problems would be solved.
There should be a reward for winning lane, you should be ahead to some extent if you win lane, but bot lane has the potential to be so much further ahead than mid, jungle or top, which is why it's such a dominant lane right now.
TL; DR The problem is bot lane never goes even. One ADC is a god, moving at light speed doing 1500dps and the other is farming their junglers krugs to make their cs look better...