Adding touch to OS X would bound to be disappointing. Plenty examples of this challenge. Ultimately the use case for touch on legacy desktop OS is minimal. BUT you can’t run iOS without touch and it remains a huge challenge to have a multi-modal API..
I have always been on the side of touch being useless on desktops/laptops. But proponents of this feature have disagreed, putting forth many justifications and success stories, even if anecdotal, with Windows 10 Ultrabooks. Even though I am rarely convinced, I can appreciate how touch can come handy for some activities – mainly clicks and scrolls — especially since iPad with Bluetooth keyboard nullified benefits of laptops in some situations for me.
I believe the request from the proponents to Apple is to not make a decision for the end user, not attempt to identify purpose for, or lack thereof, touch. Put it in, let users benefit if they think they can. Unfortunately, I do not think Apple ever introduces an interface to a platform without their justification for and user story behind it.