Mainly because not many people know how to go against this odd champion. Urgot has been underrated and ignored about as much as atroxx by riot for the past few years. Luckily our crabby friend is due for a rework next! after being shifted down 1 rework slot behind galio.
Urgot is hard to play but once you master him it is hard to deal with him. Urgots late game and lethality build is very effective.

Start with an auto attack for his passive proc (Urgots passive makes the enemy auto'd lose 15% armor and magic resist for 2.5 secconds) Then hit E on the enemy champion which will make urgots Q a lock on ability as long as you aim in the general direction. If the enemy is getting away hit W for the shield and slow off of abilities. If all fails and you end up getting dove hit R while the enemy is under tower and it will suppress them but you will swap places with the original place that the surpressed enemy was