Seems like the site is growing by leaps and bounds...and slowly losing the quality we've all grown to rely on.
In fact it seems like almost every day now, there is a new thread with people worrying that the quality of submissions has gone down.
The problem is that, getting frontpaged, is so damn easy. For example there is now a front page thread with 2 points. So once HN hits that threshold of crappy users, you'll see the quality take a sharp dive overnight.
So why not make HN invite only to keep the quality of posts up? If you want to read? Nothing will change. Want to post? Then you better get an invite from a friend or wait a few months for the registration to open.
People have been saying that for most of News.YC's life. Certainly for longer than you've been a user. And your proposed solution is also one that's been discussed since before you joined. So ironically this submission appears to be an instance of the type it seeks to prevent.
Incidentally, your second option is impossible. There's no downvote on submissions. The way to push a story down is to upvote other stories. Or if it's really lame to flag it for deletion.