Enishi really needed to be defeated...
Because he accumulated a lot of hatred inside him, he could not pass his stage of mourning, therefore he stayed with the resentment forever, becoming an adult even with the mentality of 15 years ago.
At last Enishi can rest from all the pain that he had suffered all this time... I hope he recovers and goes back to his life, although in shonen manga the concept of "redeemable villain" is already overexploited, I think in ruroken This type of villain was necessary since the topic are about remaining tied to the past, to resentment, to the bad things that they did to you or you did and deciding if you want to change or not, something that Enishi went through in this last fight.
I never thougth that such a simple and basic shonen can have a very cool meaning.