There is a good article about the Top 40 in the Guardian today:
http://www.guardian.co.uk/music/2009/jan/22/top-40-music-chart
"After years of disposable dross, the charts are returning to a golden age.
So the charts we have now are closer to those of the 1970s and 80s, when hits were genuinely, enduringly, unifyingly popular, rather than transient blips."
Maybe the charts are "closer" to those of the 70s/80s - but only in terms of the "chart life" of singles.
The cultural/financial status/impact of the Top 40 is nowhere near the levels of the past.