[quote]Quality writing is nice, but no matter how good it is, someone's response is limited by how much is given for them to respond to. [/quote]

Double-edged sword right there. You're addressing the medium by which we communicate interaction as if it was the determinate factor, and it's not. You're missing the real factor on what an individual has to reply to: content. What is dialogue? Often, they are several one-liners back and forth of characters just speaking. Yet, technically, they are sentences. In that scenario, that is adequate. You could say, "well, fine, but in conversation, you're limited to relpying with more conversation", and that's not true. If a character says something to upset or enrage another character, that character can react in a myriad of ways ranging from decking the speaker to bursting out in tears. 

Interaction is the key aspect of roleplay, plain and simple. Thus, every post we make has to communicate using the same encoding/decoding/message/decoding/encoding/feedback setup as any other form of communication, including elements of noise, environment and medium. When you say quality, what do you mean? The literary technique and skill applied to a single sentence? Or, do you mean effectively encoding that message in a way that will limit noise and listener decoding issues? Both are applicable. Sure, you can give more content, more quantity to the message, but to what avail? 

The real aspect to look at here is the message itself, the content. When encoding and designing the message, understanding how much information and how to structure that information to create the best possible feedback and illicit a response of similar caliber should be the goal. Quality and quantity are just aspects to that message and can vary from situation to situation. That would best promote proper communication and thus support the interaction within a roleplay, which is in fact its primary element.