Because of THEORY (both organizational and marketing).
Web 2.0 technologies - such as the CanonRumors forum, enable customer-to-customer communication
Big organizations do not want their customers telling them what to do, rather they would prefer if they could dictate to their customers. Marketing textbooks state categorically that 'Marketing Strategy' should be organizationally-led and that they (companies) should seek to influence customer behavior and that under no circumstances should companies lose control of that strategy. Big corporations may even use focus groups to discover what their clients think about their products (think CR site today), but then they go and use this information to tweak their product & marketing strategy (pricing, features etc), not to define it. However the Web, specifically Web 2.0 allows for user-generated content and interactivity, which creates a major headache for large organizations like Canon Inc.
If large corporations did what their customers want from the get go, there would never have been Guinness Light, or New Coke vs Classic Coke, and GM would never have launched a car in Latin America called 'Don't Go' (the Chevy Nova).
It would be great if big corporations listened more to their customers, but then why have a dog (marketing dept) and bark yourself?