What's the story on this?
He writes that he felt good about the RAH concerts even though he was sick with flu, but that doing it for Ginger's and Jack's pensions made him feel better and that it was a worthy closure of the Cream chapter which was always unfinished for him. But he regrets being talked into the US concerts ("if only we had stopped then" - meaning after RAH), because by then Ginger's and Jack's sour relationship had reared its ugly head again and the band was underrehearsed.
I don't think Bruce's bass sound was feeble at all with the Cream reunion concerts, it was lyrical (as it should be). Bruce has never had a fat or domineering bass sound. He doesn't play that way and his often introspective bass playing wouldn't go well together at all with a very full sound. It's just like Baker's drums don't sound "phat" by modern standards either, nor should they. Baker's drumming is like an animated intellectual conversation with the other instruments, I'd hate to hear it clad in the "crash, bang, wallop"-armored drum sound so en vogue at live concerts today.