If you are aiming for a game that people play for more than 1000 hours, sure. Commercially, this would be a terrible segment of the market to aim for. The people who play the same title for that long are unlikely to buy your game, because they don't have time to play it. Unless you happen to find a niche first, you will end up with a few players, but supporting them for a long, long time.

Shorter games are fine, and sell to people who want novelty over repetition. Don't make the game longer than its content, and price accordingly.

It doesn't make a game better, it just superficially defers the realization that the game is played out. Yatzee's only claim to being a game is that you roll dice... if you didn't, people would immediately see it as the pointless activity it really is. Video games are no different. If you put 1000 hours into a game, you will see it for what it is, and proc gen is not even a factor at providing interesting gameplay at that point. A game ultimately succeeds based on the merits of the structure it actually has.

Now, if the proc gen is sufficiently complex, we're talking about something else, (but that is rare if it exists at all.)

OR:

C) have 1000 hours worth of manually created content

Think about games like witcher 3, tes, fallout. Those things are huge and replayable.