Well, it's half bull. Apple _did_ have market data as they had already launched the Lisa and had seen what worked (and what didn't). People did like the bitmap display and mouse interface, but couldn't stand the cost or lack of applications (note that mac development was well under way when the Lisa launched).
In addition, they made a lot of changes post launch due to market acceptance, e.g. size of storage, cost etc. The Mac benefited from the fact that Apple was willing to stick with it even though the Apple II was still the cash cow and the Mac struggled.
So it's bull in the sense that they were quite attuned to what the market had to say.
There's an important difference between market data--which comes from actual sales--and market research, which is done prior to the launch (and sometimes even prior to the development) of a product.
Apple pays very close attention to market data, and it obviously informs their product development (see the big iPhones now, for example). What they tend not to do is market research: surveys, polls, focus groups, etc.
In addition, they made a lot of changes post launch due to market acceptance, e.g. size of storage, cost etc. The Mac benefited from the fact that Apple was willing to stick with it even though the Apple II was still the cash cow and the Mac struggled.
So it's bull in the sense that they were quite attuned to what the market had to say.
But it's not bull in the sense that they really did go their own way, almost fatally (e.g. no floppy -- http://www.folklore.org/StoryView.py?story=Hide_Under_This_D...).