It's not just record labels, it's advertising in general. Most people don't realise how much they're affected by it. The video here shows it to great affect:
http://www.channel4.com/entertainmen...uggestion.html
Not until you start paying attention, do you realise just how easily manipulated we are. When you start exploring new music, the majority of the mainstream music loses its appeal. Even then, the record labels have got their marketing machine at work. They create a sub-genre of alt-pop like REM, Athlete, Snow Patrol etc. These types of bands (while being perfectly listenable) are specifically targetted at those wishing to break away from the mainstream.
Is mainstream music getting any worse? I certainly find it hard to listen to, and lacking in any real atmosphere. There's a few songs that are OK on a night out, but I can't think of any I'd chose to listen to at home. There's many from the past that I do listen to, probably because I grew up with them; they bring back memories.
Dave