Re: Do some people really think Larry Bird couldn't dominate like he did, in this era?
Bird would be very good in any era.
Could he play the 3 as he did back then, well, I wouldn't want him defending the 3 versus the present athletes at the position(and indeed he didn't necessarily do so back then, when on court with McHale, McHale usually took the better offensive player).
The defense back then is being overhyped somewhat. People seemed to concede the J back then a lot more (possibly a relic of the pre-3 point line era), and the percentages do seem to show that defense wasn't as good (relative to the eras offense), and that so many of the eras scorers were small forwards (Dantley, King, English, Wilkins, Vandeweghe, Tripucka, Aguirre, Marques Johnson, Purvis Short, Jay Vincent, Orlando Woolridge, Xavier McDaniel, Mike Mitchell, John Drew plus others that verged on the era and/or swung between the 2 and 3 like Wilkes, Erving, Walter Davis (mostly a 2 in the 80s but played both), Dale Ellis, Ricky Pierce, Chuck Person, Eddie Johnson and Calvin Natt). So I do think that was a position it was easy get points from.
Of the defenders OP lists, the first set of genuine elite defenders, few played their prime with Birds prime (and there are some like MJ who I'm guessing weren't regularly covering him). Maybe only Cooper and he wasn't a starter.
Sellers was lousy, most of the "athletes" were poor defenders, I would have assumed Cummings and Grant were covering McHale, and Clifford Robinson played Bird a grand total of 6 times and played less than 20 minutes per game.
Not that I don't think Bird wouldn't be able to play now, non-athlete shooters like Nowitzki and Kevin Love (and the following group aren't in Bird's class clearly, not that the above were, but just in terms of fitting the shooter, non-athlete, rebounder forward type) Ryan Anderson, Ersan Illysova are thriving and Bird is the best. Would he get the same numbers, well not in terms of raw numbers at the slower pace, lower % era. But advanced metrics would be roughly the same, maybe the wing defenders are a little better today, but roughly he'd be playing as well as he did.
On the plus side he probably wouldn't bust his fingers playing softball and would have lasted longer with regard to treating all the injuries.