From the IT perspective, usability was never an issue before the Web because of the way in which their business model worked: by the time the user encountered any difficulty with a software application, he had already handed over his money and had to deal with the product. In the consumer markets "no refund if the box has been opened" was a standard; and in the business market, it would be difficult for an executive to admit he had made a very expensive mistake in buying software that was no good.
As such, consumers were faced with a choice, learn to deal with the user-unfriendly aspects of the software they had purchased, or pay out again in hopes that another product would be better. Most chose the former, and as such the software industry came to take it for granted that they could turn out a mediocre product and customers would accept it.
The business perspective is little better: until the industrial era increased competition, the consumer's choice was to buy from the one-and-only purveyor of a good or do without it. So long as they were willing to pay the price, retailers had no reason to believe it was too expensive, and so long as they were willing to suffer poor service, retailers had no incentive to do any better.
Even after the industrial era, retail remained notoriously customer-hostile. Once a customer invested the time and effort to travel to a retail location, he faced a choice between accepting poor service or taking the time and effort to go somewhere else - and generally chose the former, as there was little chance of getting better treatment.
The Web largely changes this: if a Web site is flawed, either in terms of its core functionality or the level of service it provides to the customer, the competition is just a click away. The customer is no longer constrained by a lack of options, or the difficulty of leaving the "store" and going elsewhere if anything about the experience is not to their liking.
And yet, these two factions remain mired in their traditional mid-sets - in spite of the consequences, and blind to the fact that the sites that lead the field in every category are those that are customer-focused.
Given that the consequences of indifference are now visited upon the indifferent, perhaps it's only a matter of time before they realize the consequences of their complacency. However, it's taking much longer to sink in than one might expect.