Ez has been the most played adc for a long time now, simple, he is the best adc hands down unless your are playing protect the vayne/kog.
Tell me how many games Ez has been in and how many Urgot has. Not hard to understand really.
The take golems conundrum is false way to validate your point, any bot lane can get double golems. Has no relevance in this discussion.
Other things i want to add are Urgot is better with his team for 2 reasons, Ulti and protection since he has no mobility. Without mobility its hard to win in solo Q. Second thing is armor was nerfed and urgot primarily itemizes armor because he is an anti-carry. Also mana has always been an issue for him, run out of Q's and urgot is pretty useless. If you want you can waste a vital item space for a manamune but while you have a Glacial, Brutalizer, and Manamune, that Ezreal has a Bloodthirster and any combination of Zeal/Phage/Glacial/Sheen for his Iceborn/TF/PD/SS. He will also be higher CS and can push your lane. Urgot pushing means using Q's and using Q's means oom. Here comes lee sin for a gank, good luck with no mana or mobility. Get the point?