I can’t even pretend to say I have the answers, since you have hundreds of souls to look after. Still, there are some things I’ve found useful to consider.

One reason RP is so dreaded is that it involves applied effort in so many areas: Description, Role, Emotes, Actions, and Dialogue (DREAD).

Your problem is that roles are under-emphasized. The Role drives the action of the character, and sets out the character’s understanding of the world. The remaining aspects of RP are like extraneous limbs. Without R, you just have a DEAD character. It seems absurd that Descriptions are required, but Roles are merely recommended. It’s almost as though you’re requiring our characters to have faces and bodies, but brains are optional. If so, therein lies the problem.

Other than that, most of the players are capable of RP if they put forth effort, but they need motivation. Your basic players will only do as much RP as is required of them. After all, it takes a large measure of thought to create a good description and solid role, and especially if you want heightened effort, people need to feel Acknowledged.

Basically, all of your little tidbits are useful, but people still want to see more of them, and more often. Offering immteraction or quests is great for some players. Handing out savoury exp for good RP also seems appreciated. If you have limited staffing to police or reinforce RP, then you can expect role depth and sophistication to suffer. You may simply have to allocate more resources to bolster RP. There’s no real substitute for Time.

Another observation is that many players are number-crunchers, and you can only expect so much of them. They often have limited patience for RP, and they expect immediate, tangible rewards for any RP-related effort. Getting them to write complete sentences is like pulling teeth. You will need a very patient, inspiring, and determined set of IMMs in order to elicit enthusiasm from them.

I hope these basic thoughts make sense of the abysmal RP you've seen. So far, the only element of DREAD that you’ve generally taken care of is “D”, by requiring descriptions. Unfortunately players still can't READ. To inspire them to READ you’ll need to put out more of your Time and Acknowedgements (T&A).

I've learned from my characters that if you give your players enough T&A and they'll RP all you like.