Personally I don't buy into this "so and so will be coming into their prime in x years", based on an age of around 27-29 usually. I think players mature at different times and in many cases their prime may actually occur at an earlier age. For example I doubt Michael Owen will be much better at age 28 than age 21, a bit more knowhow and experience etc (remember he still had 3 years international experience, including 2 major championships at age 21), but perhaps a little less pace, his most important attribute.
Other examples would be Ronaldo, I think he may get back to his old level but will he surpass it significantly? Giggs is another one. And then you have the likes of Lee Sharpe, whose top flight career was basically over by the time he reached 28-29, yet back in the early nineties he was practically a legend.
You could argue that england would be wasting talent even more by not picking these exciting young players. However I do agree that players shouldn't just get in he squad because of their "potential", or how young they are. Down the years the England setup has largely ignored mature, proven club players like Ian Wright, Matt Le Tissier and Ray Parlour, maybe Robbie Fowler too. None of these ever get what I would call a decent run in the side that their club form merited. Meanwhile the likes of Phil Neville were getting picked for the squad practically every time.
Beattie has more claim to a place in the squad than Jeffers or Vassell in my view, not that I think they are bad players but he is the leading scorer in the premiership afterall. I wonder when the last time the leading non-retired english goalscorer in the premierleague (assuming 20 goals+ reached) didn't get a place in the england squad... wouldn't suprise me if it was Ian Wright.
I would really like to see what would happen if we gave David Platt and his u21 setup the chance to pick whoever they liked and create the nucleus of a team for the future. Robinson, Barry, Prutton, Defoe, Cole, Rooney, Carrick (too old?) etc.