There were people on these very boards who said they were unlikely to buy 4Ed because of the non-renewal of licenses to Paizo for the magazines, and the cessation of the Dragonlance license, etc. Some even called for a boycott.
The announcement of class & race exclusions was a detriment. From a marketing standpoint, it was a tactic that could only hurt sales. Why? Because that announcement turned off people for whom those excluded features meant their favorite race or class was gone, or that their campaign was non-convertible. By simply staying silent as to those changes, that group - or a portion thereof (esp. those who pre-ordered the books)- would not have known about the unpalatable change until after the product was in their hands. There was, in addition, no indication that for those who viewed these changes positively that it was a selling point. IOW, while they may have liked the racial or class changes, those changes were not a deciding factor in whether they intended to buy the game. More often than not, people cited dissatisfaction with 3.X in general or certain mechanical changes as being more important selling points for the new edition.
And while better marketing may not have converted anyone to 4Ed, it probably would have meant more sales. Those sales would be to people who might have bought the game and still not converted, but for being turned off by the marketing campaign.