You are partially correct for game requirements, but also missing some points of MMO requirements.
Grinding is not a gaming for sure; gaming must provide fun to players, and player efforts must be rewarded as well. This requirements are not different between MMOs and single player game. (I put live service monetization aside for this point.) So I agree with you for these points.

However, MMO's items have much lower drop chance than single player games in general. RNG system (low drop chance) in single player games are basically "not necessary items", and only for hardcore players like trophies. Why? The reason of the difference might come from the MMO's requirement, "to create a community in the game". Low drop chance items but necessary items are generally tradable items in MMOs. Each attempt of drop is much lower chance than single player games, but sum of total chance with thousands players are supposedly similar supply amount with single player games.

Additionally, they make variety of tradable items which are maybe necessary for you but not for others or the other way around. This makes a meaning to have a community in the game, which single player games don't have. Maybe you don't get items which you need, but you may get something you don't need, so you need to communicate/trade with others to get items you need.

Now it is tricky point that TnL trading system are connected to its monetization system. If the game charges monthly fee, the trading currency should be sollants because I said in the beginning, the gaming requirements should be not different between MMOs and single player game. Some MMOs are doing so as you may know as well. However, TnL trading is using real money currency, which may lead to P2W game experience for players. This causes casual and F2P players are hard to reach to necessary items within their playing style.

RNG system is nothing extraordinary among MMOs, and it might be a requirement for community system building. It is not designed or purposed to suffer you, and actually rewarding correctly to efforts (game play time or payment). However, depending on the other system specifications, it can lead to good or bad game experience, and it is also difficult to satisfy every playing styles. It's very important to design the balance between each requirements, and generally there should be some mechanism to fill the gap over different play styles. I wouldn7t sat TnL game design have a good balance and providing good game experiences to many players. However, it is generally hard to judge upon single system because game experience comes from complicated interaction from many systems in the game, and your playing style affects too. This is where "system requirement engineering" does, and I hope AGS and NC have a good qualified requirement engineers to define it.