Because I hate it a lot. Less is more.
@OMGrant Sorry, but this is really too few information!
I guess you mean the new OSMC skin and you can configure the new underline feature at
GUI -> Settings -> Interface -> Skin -> Configuration -> Advanced -> Hide underline text highlight
For any thing else, please, provide more detailed information. Screenshots would help, see this article how to do that.
You nailed it. Thank you Jim.