Running your own Bitcoin node does enhance your wallet security. You can process all your bitcoin transactions via your node rather than using one provided by the wallet provider. I have cold storage via a Linux OS on a USB stick which has never been online but it still relies upon the wallet providers node. When I get my own node I can connect my wallet via that= enhanced security for cold and hot wallets. Agree there is some cost on electric to run computer but probably only a few dollars a year or in my case now ~ free solar.