If you must feel that sense of accomplishment (which I really doubt you do. There's a reason synthetic opiates are so addictive), I can just give you that too. I'm God, after all.
It isn't about a sense of accomplishment. I agree with you, the drugs pretty much outclass any natural sensation and they're only getting better. Anyone who says that a sense of accomplishment feels better than drugs hasn't tried drugs. But sensations are not ends in and of themselves. Hedonism is a dead end.
Pleasure is its own reward.
No, it's not. Pleasure out of context is worthless. It's just a transmission of meaningless data.
Pleasure is a functional process. It has a purpose. It rewards you for doing things right and trains you to come back and do things right some more. It's part of the suite of heuristics by which we navigate the world and learn how to function.
Your emotions are there to program you. Pleasure tells you to keep doing whatever your doing. Pain tells you to never do that thing again. Ambition and greed make you climb the social hierarchy. Lust tells you to go have sex with a pretty girl.
Emotions drive us to go out and live life. They're processes in our mental code that push us around and teach us. And they're fine for that.
What would be the point of separating an emotion or a sensation from the rest of the program. It's literally like stripping a random chunk of code out of some computer program. The process is pointless on its on. It only has meaning as a functional part of the machine.
Do you really want to be a barely sentient pleasure loop? If you lived in constant ecstasy you would barely be alive. You would just be a broken robot. One circuit telling another circuit that everything is great. And that's all.