Scoring runs in the AL East has never been difficult for Yankees, Redsox, Jays etc. These teams win when they have starting pitching.
The reason its better to invest in young pitching, is because you can always find players who will do well in these parks. Look at the Jays, Edwin, Bautista, Saunders, Travis, Donaldson, These are all players that we didn't draft or develop and yet they are our best hitters. Same with the Sox in their hayday, manram and Ortiz were not developed by them, they were just guys (Manram less so)
Pitching is the commodity that is beneficial
In the NL however its the opposite. You can always find guys who can pitch in those pitching paradises and pitch to 8 hitters and 1 free out every three innings. They need to invest in young hitters to excel.