...with the format versus Format style.
What is being done now with >F<ormatting is a tight control exersize of the music played...so in the different >f<ormats...all are ending up as you say...the Top 40 of modern rock etc...
So maybe I missed your original play on Top 40...but in essence it has degenerated to a Top 40 rock, Top 40 adult contemporary, Top 40 hiphop...so I'll concede to that...but not in the historical [link|http://www.radioexpress.com/ewklyprog/eat40.html|Casey Kasem] sense. There was a time with the Billboard Top 40 was a radio >f<ormat...you played those songs...plus some older ones from the same list...tossed in a few throwbacks and repeat...old pop radio. What the F brought was that same mentality for all the little fs...but not in response to the existence of Top 40.
The problem really is the demand from the ratings and demographics folks and their "need" to establish a tighter control over those you "appeal" to. (to the detriment of those who appreciate music). Its not a "Top 40" mentality though...its a branding attempt (Magic", B-one o, Z98...yadda)...an attempt to burn your brand into the psyche of the listeners.
The problem is, cost of stations is now so inflated (thanks Clearchannel) that folks with vision and an alternative cannot afford to play anymore. Those with vision are few, far between and are all among the 20% of the remaining stations that weren't gobbled up in the past 15 years.
And it promises to get worse...as they are now removing the DJs from the equation...and automating the stations completely.