There's always been tons of insubstantial works in all forms of entertainment/art, and there'll always be some gems between those. Seriously, it's not like there was another [insert favorite anime here] every year in the 90s, and nowadays all that's released is brainless trash.
Also, moe trash is the best.
Doesn't mean there isn't currently a clear decline. Of course there will always be insubstantial work, but if you hold something to its highest points over a timeline you can definitely trace changes in the nature of things.
And the best anime have been growing worse over time.
Regarding your first point, I think it really comes down to the medium as a whole being shallow. They're typically glorified commercials for the source material and the anime originals vary so much in quality that there's not a lot of room for comparison. It's hard to capture the same charm when you're working with less creative freedom, harsh deadlines, and an industry that's rapidly evolving. For better or worse, the consumers interests change and the industry is only still afloat because they're able to make sales. It sucks, but what can you do other than support the studios that you think do it right.
The medium has the ability to be better than the sum of its parts, just like all artistic mediums. The industries rapid evolution is what is killing it, and that is for worse. Even if we can't change it, that doesn't mean it's not happening. It just means it is.
I've read some excerpts from the Miyazaki interview and I don't think he's really one to talk given his formulaic approach to sell his films. He can reel in viewers with touching family films, others do it with pantie shots. I'm all for "artistic quality", but I think there's still some merit in giving people what they want. Good shows won't go away, you'll just have to search a bit harder to find them.
He actually acknowledges that a large part of his early career is to soft, and toting happy nature, which is why he made Princess Mononoke so ambiguous, with no real villains or hero's. You should look more into it. The guy is thoughtful as hell. Good shows definitely won't go away, but it's unfortunate that good shows come about less frequently.
As nice as those are, you have to consider what entertainment is. People purchase (or pirate) anime first and foremost to be entertained. Whether or not it has any significance or meaningful messages is secondary for most people and there's nothing wrong with that. I was in a similar boat to you for awhile where I looked down on the endless harems and brainless moeblob comedies until I spoke with a high school student about why he liked Sword Art Online, Shingeki no Kyojin, and other mainstream dreck. He explained that his mother died and since then, he looked to anime for the imaginative worlds and obvious wish fulfillment. It made him happy. He said he didn't need complex stories riddled with meaning, he just wanted something fun. It was a chance to turn his real life off and enjoy himself. I felt like an idiot for not realizing that sooner and since then, my views on the subject have lightened up. I also remembered it was true for other mediums as well. It's why people like generic pop music and dumb popcorn movies. So while these insipid shows keep getting churned out, I can't fault them too much because they make people happy.
If you view anime as purely entertainment, of course you're ****ed. Same goes with music, and movies.
It's great that the person you talked to could use anime as an escape, but that doesn't speak to the quality drop. People will find escapism always. One of my closest friends uses video games to ignore his dads cocaine addiction and his bipolar sister. It doesn't speak to the subject matter though, and it doesn't mean that that content isn't bad, and harmful to the medium.
It's about striking the balance between making people happy and making substantive content. If the object was to just make people happy, then of course, make anime as it is now, and have Michael Bay direct every movie, and have all music be radio pop, but that's a bleak future man. Brave New World portrayed that kind of dystopia, and at the time, and now, it
is a dystopia. The pleasure bots are taking over. They've got enough of everything as is. Art and entertainment need to be taken back. A balance can be struck, but it won't be by blatant acceptance of these entertainments new forms and roles.