"On Sept. 14, 1966, the Gemini XI spacecraft is tethered to an Agena target vehicle. Gemini XI command pilot Charles "Pete" Conrad and pilot Dick Gordon are maneuvering their craft to keep the tether taut between the two. By firing their side thrusters to slowly rotate the combined spacecraft, they were able to use centrifugal force to generate about 0.00015 g of artificial gravity."
Why this is not being used now ? I guess because it was not seen as a priority for Apollo and followup (US) missions as they usually took just two weeks at a maximum. Health effects of microgravity have been also understood in more details & how they can be overcome for the short flight durations.
With the ISS & missions lasting half a year (and longer for some crews) artificial gravity would indeed be more useful, but hard to pull off for a big permanent installation like the ISS,
that needs to maneuver to accept spacecraft while also providing reasonable microgravity environment for experiments.
I'm no space engineer, but even I can spot a huge number of problems with going with a cable-counterweight system.