What this thread really demonstrates is that the "problem" of plantations is multifaceted.
1) Luxury drinks only get demand at SOL 15. So, coffee and tea are not good bets for heavy early game investment.
2) Except for obsessions, there is no real need to get serious about investing in certain intoxicants. Liquor can be made on rye farms that are quite common and in factories. Why would I make the effort to secure tobacco? And while wine is a plantation good, it can be produced all over the map, so, again, there's no need to get super invested in it as a good.
3) Some plantation goods have multiple sources. I've already mentioned liquor, but we can't really forget fabric. And let's be clear: fabric comes from livestock ranches. As far as I know, livestock ranches are the only type of agriculture building that can be built
anywhere. Sugar is another one. I can get sugar from farms all over the planet. While the plantation buildings are far more efficient at producing these things, there isn't a driving 16th Century desire for massive sugar plantations as such. And that doesn't even address dye.
4) Goods substitution in the game means that POPs care less about prices than you think. From the wiki:
Notice that prices are not important here. It's market share. This leads to bizarre outcomes like this:
Why is coffee in such high demand despite lower prices on wine? Because of market share. This is Austria, by the way, so this isn't a case of obsessions skewing results or something. POPs could buy more wine to replace coffee demand, but they won't due to market share. I picked this screenshot specifically because it's the exact opposite of what people are reporting in this thread with coffee. I have a ton of demand for high priced coffee... Despite prices making wine look better.
Even worse, wine can get demand from other buy packages, so why aren't they drinking more? Goods substitution.
Bonus points for tea:
Yeah, those POPs could be drinking more tea, too. But they aren't.
All that being said, I'm not 100% convinced that plantations are in a bad place right now.
Much virtual ink has been spilled talking about plantations should be more or have more demand or be more profitable. But I'm reminded that during the period, there were plenty of situations where plantation style agriculture simply didn't make that much money. The example that always comes to mind is during the ACW. The Confederacy's attempt to make "Cotton King" was a miserable failure. Britain simply got cotton from other sources.
Sugar is another one where economic pressures made a plantation style economy less viable over time. Unless my sources are wrong, beet sugar accounted for 2/3 of sugar production in 1899. And the process of converting over to beet sugar was started before Vic3 starts (Napoleonic Wars).
Plantation style agriculture wasn't magic. It had to face economic pressures just like everything else in the period. I'm not sure I dislike its current place in Vic3. It's certainly not historical at game start (tobacco, sugar, and coffee really should be more valuable), but these things also shouldn't be dominating the world market for decades on end, either.
To be honest, I think what's really going causing these issues is a combination of factors.
1) It's too easy to conquer a colonial empire that has those products super early in the game.
2) Goods substitution doesn't do the market any favors in these situations.
3) There is no differentiation between cotton and wool.
While I'm not too concerned about plantation goods in Vic3, if these three issues were addressed, it would probably make the situation better.