Comment by Animats
A "standard servo" of R/C toy type does have feedback. It just doesn't come out the standard 3-wire interface. Robotics hobbyists have been fighting this for decades.[1] There are "digital servos" for R/C, but they have the same 3-wire interface. They just have better motor drive circuitry. Dynamixel [2] has been selling R/C type servos with a digital interface for years, but they are somewhat overpriced. It's a tiny product niche.
Rod Brooks' original insect robots used R/C servos where someone had wired in an extra wire to extract the analog error signal. This provided force feedback. So that's quite possible.
The general problem with servomotors for hobbyist use is price. Note that the OP was given those motors as an influencer. Industrial motors with encoders are expensive, and controllers are worse. Some years ago I was talking to a Maxon rep at a trade show. They'd just introduced their own controllers. He told me that the motor and the controller cost about the same to make, but the controller people were getting 90% of the profit because controllers had become cheap to make. So they built a controller to improve their margins.
FWIW (having used Dynamixels for 13+ years for hobby stuff), there are cheaper alternatives with tradeoffs now, too. Though I've only played with e.g. AX-12-sized ones (specifically HiWonder HX-35HM sitting on my desk from early last year)
There's so much to do in robotics, that you won't catch me going back and modifying RC servos, ever. I'll do hard things elsewhere! (And I don't even do autonomous hobby robots...)