Interesting question this. England have usually been crap at cricket for the last twenty years. So it's probably got something to do with that.
To look at it from another perspective, you could ask: why are other countries producing ATG players? Pakistan in particular is a pretty strange case. Especially if you change "ATG" to "phenomenal talent". Why do Pakistan keep getting players like Wasim, Waqar, Inzamam, Saqlain, Younis, Yousuf, Asif.. even Aamer? Without wanting to get into debating the merits of any specific player, England really haven't been producing players of that level. On the other hand, they can call on plenty of solid middle order batsmen or backup swing bowlers to do a job when their front line breaks down. As we saw during the summer, once you shave the top-class surface off the top of Pakistani cricket, there really isn't much at all underneath- especially in batting.
I would maybe hypothesise that coaching and infrastructure are what it takes for maximising the potential of the above-average talents in cricket, but mass participation is what gives a country a good shot at producing some of the seriously good players.