You only discover force touch if you mistakenly use too much force at the right time and place, which isn't an everyday occurrence. Where as a right click function could be discovered by clicking randomly with the right button which was obviously put there with purpose.
But option and force touch.. its unclear when its applicable, what it’ll get you, if it even went through and for option, where the resulting button even is
There was no way to know in advance if right clicking a particular thing would provide options or not.
Force Touch has no physically or observable clues to it's existence and thus does not encourage experimentation and exploration.
Despite the fact that there was zero indication that right clicking a particular thing in Windows 95 might actually do something, and the fact that there was always an alternative way to access that information or function for those who only had a one button mouse, we managed to adopt the right click functionality anyway.
Force touch is no more a secret than the adoption of the right mouse button was in Windows 95.
I don't think you understand discoverability at all.
People know there's a right mouse button simply by looking at the mouse. They might not know when or where to use it but they can see the button and know it has a purpose. The button invites people to press it and they might randomly try it in various places to see if it does anything and discover a feature. The OS is irrelevant.
You can't see Force Touch. You don't know it's there until someone tells.
Looking at a machine you had upgraded to Windows 95, you had no way of knowing that the right mouse button now did something, nor was there any indication of which items in the UI supported right clicking and which ones did not.
I reiterate my point that force touch is no more or less discoverable than right clicking was in Windows 95. They are both optional shortcuts to reach functionality you can already access in another way.