Seriously, go to http://reddit.com/reddits/ and get rid of things like r/pics, r/gaming, and r/funny. Subscribe to a sub-reddit that has content you like. It's not like the good stuff is hidden away never to be found. Just look around a bit and you'll find a much more enjoyable experience. That's reddit's power.
I remember the day I learned that some of my new co-workers were really into Reddit. It was strange because I remember thinking how superficial their lunch-time conversations were compared to what I'd been used to debating online. It was an "aha" moment. Here comes everybody.
Reddit is, and has always been, a large organic community that has always undergone change. Reddit had to introduce subreddits as a way of breaking up and categorising communities as things outgrew the "everything on the front page" model.
Getting big changes things, and I don't see how comments like yours are insightful when all the things you listed (yes, even the deep and meaningful posts and debates) are still happening on the site, your just need to sort through the noise.
Things like subreddits help you do that and get what's relevant to your interests.
What's interesting about reddit, is that's a way to preserve the quality. Reddit is like a hipster dog chasing its own tail. As the popularity grows the quality keeps moving to ever newer sub-reddits.
Personally, I have few qualms with the quality of the content on reddit. I think the subreddit subscription model the site is centered around did an excellent job at helping users weed out content they weren't interested in.