Many of the popular professional mixes today are loud, but lack dynamics. This has the effect of encouraging more of the same flat, loud mixes because “everyone is doing it”. It is possible to have it both ways, though. With a few easy tweaks, you can have a mix that is both loud and dynamic.
You can read the full article here: http://en.audiofanzine.com/mastering/editorial/articles/get-loud-masters-without-overcompressing.html