I agree with this. The cabinet minutes wouldn't have revealed anything interesting, for the reasons you describe. The evidence is that Blair didn't even need to buy any of them off, except for Short. The reason the government doesn't want them leaked is not because they contain anything explosive, but because they will reveal how supine and mediocre the Labour front bench was and is.

The Campbell Diaries, even in their censored form, are a useful guide to the period. He rarely mentions cabinet members outside of the Blair coterie, except in order to express irritation with them.