Replace drugs with machine and we already have such a thing. However the pleasure from drugs is stigmatized and prohibited, and the addiction to the pleasure machine is seen as life destroying.

IMO - it's not the pleasure itself that is stigmatized, but the side-effects. Side effects including deteriorating health of the user, as well as the occasional resorting to immoral or even criminal means to feed the habit.

There's also a whole dog-whistle aspect to the 'war on drugs' (e.g. massive differences in sentences on crack vs. cocaine offences)

A game is more fun without the cheat-code.

You live life with significantly more "cheat codes" than the rest of the world, now what makes you think you aren't already living with "cheat codes" you aren't aware of? Since you could also program your reality to enjoy the benefits of the "cheat codes" without actually being aware of them, then there's a bit of cosmic irony to your statement.

But what's proposed isn't any cheat-code, it's The cheat-code. I remember playing one of the Dooms once with its god cheat.. for a few minutes.

Because I believe in a greater purpose in life (in the non-religious sense). But that's just me

Because I happen to care about things-in-themselves, and I can have a lot of fun and be very happy with things-in-themselves. Experience machines are the kind of thought experiment invented by people who can't conceive of real life being a nice place to live, and thus constantly want to escape into the un-real.