Don't mind me jumping in here... just gonna give my two cents
But the real question is, if an art portal is created, how much use will the art forum be? The portal sounds like an alright idea, but how do you judge what art can pass or not, if it's on a grading system like the flash portal? Good work could be deleted or blammed because, as already stated, someone may not like it. Newgrounds just isn't the kind of place that you go to post art that you'd want constructive criticism on. Yes, I know that there's a handful of people out there that would, but what needs to be focused upon is the masses.
If a poll was taken, I bet that this site is an overwhelming majority of teenage males. Then look at the majority of those guys of what they do/don't do on Newgrounds. You'd probably find that that majority isn't interested in giving constructive critisim on "pretty pictures."
Though it would be nice, I'm personally not 100% for the art portal. What would happen to the art forum? How would the art being submitted pass, or how would it be considered (dis)qualified? For those who would use it properly, it could be helpful, but I think that if you want to have a place to upload your art, I'd say try Deviantart or Sheezyart. No offense to NG, love ya, but it just doesn't strike me as art portal material.
But I could be wrong. Maybe, if initiated correctly, it could be a really nice thing.
sorry for the rant, here at school, just finished my finals, don't have anything to do