Well you certainly need to know how to defend kicks. BJ Penn is also another great example he rarely threw a kick and was a great champion. But when he did kick against Diego Sanchez...
Having said that having kicks in your arsenal is not a bad thing. MMA is constantly evolving, there might be a time where kicking is absolutely necessary to win a fight. Fighters kicking game is very basic right now. There's a whole other level to kicks that we only tend to see in traditional martial arts. If MMA guys learn to incorporate this into their overall game it could end up being an extremely powerful weapon.
Alot of under utilised techniques such as the side kick. Can be more effective than a jab if done correctly. Think about it, it will hurt more than a punch and you can cover more range with a kick.
We started seeing guys like Conor use that front kick to the body very underrated and under utilised move. When guys learn to kick properly it will be as effective as boxing. Just we are still in an evolving sport that's in it's infancy.