It's just another way to maximize revenue. I recently got a Visual Studio Ultimate with MSDN subscription though my company. If I go to http://msdn.microsoft.com/en-us/subscriptions/buy.aspx it looks like that's $11,899.00 yet when I looked on our internal site it was ~20% of that of that price. If the actual price is really 20% of that why even list the price? Well most of these sites are designed to sell to billion dollar companies and only a tiny fraction of the people visiting that site have the authority to purchase their product. Ideally, your contact info has value to them, and they trade pricing info for it.

But as an upside, you can often start using the software before the sales process finishes. Which is a fantastic end run around the 'approved' > 'negotiated' > 'purchased' process which can take forever at large companies.