i do agree there is a lot of rubbish in the charts (like Pussycat Dolls, Britney, etc).
But there's always been lots of rubbish, but over time you forget about the rubbish & keep listening to the good stuff. So it seems better on retrospect.
In 10 years time, we'll remember the good stuff, and have forgotten about Pussycat Dolls. Same with all the awful awful rubbish from the 80's & 90's that we have forgotten about.
i look at the charts each week, and i find that the majority isn't awful (though a decent portion is). Its just that you hear about the rubbish stuff in the media a lot, so you assume that the charts is dominated by that sort of stuff.
(ps - the chart was someone posting USA commercial radio airplay chart)