There's still plenty of great music (although honestly most of my favorite groups, such as Radiohead and The Strokes, have released some pretty poor albums in the last year or so). The reason that most mainstream music on the radio sucks is that artists can rarely afford to take chances. With music piracy being as prevalent as it is, major label artists have to play it safe in regards to songwriting. At the same time, MTV pushes the idea that image is more important than talent. The rate of decline has accelerated in the last 10 years and especially in the last 5 years. However, we've still had:

Radiohead (particularly with Kid A)

System of a Down

The Strokes

Arcade Fire

Wilco

And various other bands and artists releasing creative and interesting music.

Pretty much agree with what you said music as a whole has been on a downward trend when it comes to quality since the early 90's. The majority of music I listen too is from before the 90's.

no the quality doesn't go downward in general only maybe the kind of music you hear and the music shown on tv (who is watching tv anymore?) but therefore there are new kinds of music which weren't even there before the 2000s. if you don't like it it's ok but that doesn't mean the quality is worse.

btw this guy combined with this music is much better than your 80s rock^^

http://www.youtube.com/watch?v=LXO-jKksQkM

I look at music like this.
There's no bad genre, just differing tastes. We live in a pop heavy music world right now. Beyonce, Gaga, Timberlake, Rihanna, Katy Perry etc. It's just what's "in" right now. Early 90's was grunge. Late 90's was rock and boy bands. Now it's pop. There's some quality pop out there, but if it's not your style then you're gonna say the 00's suck.

I however enjoy the current music scene. I teach hip hop so the abundance of good pop and hip hop songs with a good beat is greatly welcomed. I have a friend at work who hates pop and is more of a punk guy, and he has a lot of great bands he listens to as well. You just gotta know where to look and be open to new ideas.

maybe in the video above you, there are some steps you could use for your hip hop ;)

To be honest I'm listening to more and more orchestral music now-a-days... I'm always on the lookout for an excellent movie soundtrack (recently bought 'The King's Speech' and 'The Chronicles of Narnia: The Lion, The Witch, and the Wardrobe' and they're both excellent.) as well as game soundtracks ('Disney's Epic Mickey' soundtrack is superb).

As for bands... I recently discovered Within Temptation and I've become a big fan of their music (Favorite CD of theirs is 'The Silent Force'). I've also been listening to Evanescence's new CD, and I'm also a big fan of Muse's stuff (Their three part Exogenesis Syphony is fantastic on their newest CD).

the city of prague orchestra played 100 movie themes maybe you like it i love it:

http://grooveshark.com/#/album/100+Greatest+Film+Themes/4350302

How anyone could listen to this and say anything in the past 10 years is better is beyond me...

We seem to have very similar tastes i music. Ive argued until im blue in the face Wilco's newest album is on par with YHFT and the back half of King of Limbs is on par with Kid A/Amnesiac era. 

Yorke and Greenwood on Fallon (i think) doing Give up the Ghost will make a believer out of anyone. But i do agree, The Strokes have really evolved, some for the better (Machu Picchu, Life is Simple in the Moonlight) but when Julian tries to blend too many synths he fails hard.

I try to buy a new album every week. Most recently Deer Tick albums, and Foals, Young Evils, Wye Oak, Phantogram to name a few. Music itself is in a great place, its just too hard to find it unless you really want to sadly.

Linkin Park is 2000's. Hybrid Theory was 2000 and Meteora was 2003.

Blink 182's best stuff was late 90's, I grant you that, but "Take off your pants and jacket" was 2001, plus I thought Neighbourhoods (this year) was good.

I do admit Pearl Jam was better in the 90's but they are still putting out good quality music. Backspacer was really good (although obviously not as good as Ten)

And the Foo Fighters are great still, they've put out some of their best stuff in the 2000's. I'd argue that In Your Honor (2005) is as good as their 90's stuff like The Color and the Shape. Plus they haven't gotten soft at all, Wasting Light is as hard rock as their 90's stuff. 

So you're right, besides LP who are entirely 2000s, the other 3 bands best stuff was in the 90's, but they are all still active and putting out quality stuff today, especially Foo Fighters.