To chip into the whole 'hey write gooder' debate myself, writing is inherently super subjective in every sense. Sure, there's some basic guidelines and objective standards you have to follow, but getting past that means all bets are off. You have your Hemmingways and your Tolkiens. It comes down to what you're looking for in a story, and writing on a forum is no different. Shaping your writing is mostly knowing your audience; I get a little irate at myself when I find half my paragraphs are nothing but fluff(read: all the fukkin' time) and would prefer to go a bit more minimalist, but at the same time, I am a lover of detail and expertly crafted scenes.

Padding it out like an essay is the worst thing you can do because nobody likes reading an essay, but if you can delve into the psychology of your character with flowery writing and convey their emotions through more than just inner monologue, by including things like body movement and facial expression, I think a good job can be done.

It also entirely depends on 'How much shit can I react to," because not always are you going to have a forest of material to work with. In an RP I'm in currently, I'm finding players are having a hard time posting simply because there isn't a lot to post about. We're def in the most rail-roady section of the RP and that's fine given current circumstance. If, instead, we had an entire apocalypse and a 1 year timeskip to work with, I bet everyone would crank out posts that are way larger due to just having more to work with.

I actually don't think I've said much of anything that hasn't been said already, and that I may be a bit of a victim of the essay syndrome myself here... but I think there's value in not dismissing certain lengths as a whole and instead look at it on a case-by-case basis.

Sturgeon's law prolly applies too, tho.