Wholeheartedly agree with your whole reply. I would question the timing of the switch from frank opinion to faux objectivity; it seems to trace back to the 1830s when first the high speed press created the opportunity to mass-market. The editorial page serves the function of "positioning" the rest of the paper as being objective. Before high-speed printing, the editorial page was pretty much the whole paper, in my belief.
Yeah right. As if that were ever the case.
As for my own hometown paper (the Boston Globe), the blame lies at Tom Winship's feet.