This is an excellent article by andy on this subject...
http://www.safbats.co.uk/BAT-BLOG/cricket-bat/cricket-bat-voodoo-willow-and-performanceFrom my point of view, following things have happened in the last few years:
1. Players stopped caring about the longevity of their bats as they get loads of free bats from all over.
2. That means 'Pro bats' are softly pressed, most probably have lot of grains in order to play well right from the start and I assume even drier in order to get lot of wood in less weight.
Thats the reason why we see quite a number of bats being cracked or broken in
international matches these days.
I think we as club cricketers have also become impatient and want the bat to perform right from the start. Also many of us are buying new bats and selling bats just after one season of use.
In nut shell we are following the international players with the only difference is we paymoney from our pocket to buy new bats while they don't.
That's the reason why Julian's opinion has not changed over twenty years, as 7-9 grains bat are likely to live longer and turn into absolute performer after the initial preparation..