PoE's trade system does have one obscure skill

There are at least two different scales of commitment, and at least three different sub-games in Path of Exile.

The scales of commitment are: time and skill. Good game design allows a baseline rate of progression per unit time with little or "no" skill, while allowing increased rates as skill increases.

It's a mistake to think that allowing fast rewards for minimal time investment AND minimal skill, simultaneously, is "casual friendly." If by "casual friendly" one means "the game is all played out in a matter of hours and not with picking up again until the next content dump," then maybe. But assuming one wants people to play one's game, and play it a lot, getting all the rewards fast should require massive skill, and getting them without skill should take a massive amount of time.

A tutorial is taking up a player's time in order to train a particular skill, if the player doesn't have it already. Researching stuff (looking it up on wiki) also uses player time to train a skill, but doesn't consume the time of players who already have it. So forcing tutorials is only good if the player experience at a certain later point can be very bad if a particular skill is but mastered.

What's more important than tutorials is affordances. In game design, an affordance is an object which implies an expected behavior; for example, a doorknob or handle on a door says "go through me," and the design of it may even imply "push" or "pull." If you've ever noticed a door with a "pull" affordance but it's actually a "push" door, you've experienced the frustration of poor affordance design.

If the game is light on tutorials, that's fine, but the affordances for research need to be in the game to lead players to the appropriate resources. There's already a button in the game, green like US dollars, clearly marked with a $, and it takes you to the MTX shop in your web browser. That's good affordance design. It's just a shame that GGG hasn't put in a similar effort for trade indexers or the community wiki.

The three sub-games are: build design / theorycrafting, piloting / farming, and trade / flipping. It's important to realize that any one of these three could be the key point of focus to a particular player, to the point of almost total exclusion of the others. Each of these three sub-games has their own time/skill reward structure.

I feel the biggest weak points with PoE are overly low skill intensity with the farming and trading minigames, and overly high skill intensity with theorycrafting.

Although GGG intends farming to be grindy (meaning: serious time commitment), and that's fine, that's not mutually exclusive with a skill element. I think there isn't enough emphasis on positioning and telegraphed enemy attacks, and instead too much low-skill shooting-gallery style play.

PoE's trade system does have one obscure skill: realize poe.trade exists. Once that barrier is cleared (affordances!), there isn't much skill involved. The always-online trade culture generally favors those who are always available for buyers to contact, and pricing is usually just a matter of searching for similar items. It would be nice if pricing was more of a personal skill challenge and being online wasn't necessary to sell an items.

Lastly, PoE's theorycrafting is actually too deep. The raw amount of content released in this department is staggering, and there's a lot of it which is more or less junk - junk skills, junk poe items, junk affixes, junk passives. The game would really benefit from, instead of yet another update adding even more content, an update which refined and, even more importantly, outright deleted some of the dead weight.

Regarding droprates: increasing them doesn't mean you find any more upgrades. More drops mean better poe items, but better items also mean higher standards for what's good and what's junk; these cancel each other out when droprates increase, solving nothing.

Feeling like drops are shit is instead indicative of another problem: boring itemization. Deep itemization will have you consider two items with different mods and make you wonder: which is better for your build? Shallow itemization doesn't do this, so as soon as you see an Path of Exile item you immediately know whether it's trade/vendor fodder or a new equip.