Instead of the difficult task of replacing sight, motor function, or other complicated bi-directional systems, how hard would it be to simply electrically stimulate dopamine release in the brain? At its extreme, you press a button and you feel like you’ve taken a huge dose of cocaine or heroin

Easy. Been done lots of times with rats and I imagine that must be hard with those tiny brains. Brain surgery on humans must be much easier, but they are not allowed to press their own buttons. You know, ethics.

Rats will perform lever-pressing at rates of several thousand responses per hour for days in exchange for direct electrical stimulation of the lateral hypothalamus. Multiple studies have demonstrated that rats will perform reinforced behaviors at the exclusion of all other behaviors. Experiments have shown rats will forgo food to the point of starvation in exchange for brain stimulation or intravenous cocaine when both food and stimulation are offered concurrently for a limited time each day. Rats will also cross electrified grids to press a lever, and they are willing to withstand higher levels of shock to obtain electrical stimulation than to obtain food.

https://en.wikipedia.org/wiki/Brain_stimulation_reward

The lesson here is that only the pursuit of porn drives ethical, sustainable progress.