It will exist in our lifetime, unless outlawed like human cloning. This seems to be one area sci-fi media is lacking. I wonder what it'll do to animal training and how much it'll screw them up with their owners being able to directly and artificially stimulate their brains.
I wonder if we'll get the opposite too: For criminals, go through this brain pain punishment or spend XX years in jail. Well I guess we could do that now and we don't so that probably won't happen. It'll be go to jail and get zapped if you don't listen to the jailers fast enough. That kind of already happens.
Instead of pleasure, you can use pain to halt addictions too. Spend a few moments inflecting sudden pain in different environments whenever you smell alcohol and you'll quickly build a trauma response to avoid it. Not sure if that stops the addictions or leaves you in a messed up state of both wanting to have and trying to avoid the thing.