Because Wall St. owns the company. That's one of those crazy side effects of going public.
Having opened their yaps and sold the stock to someone on the basis of their own estimates, they are reluctant to say, "We goofed," so they encourage a climate of believing that they are in charge and it's Apple's fault when Apple hit or exceed Apple's estimates while so-called missing their estimates.
If what you say is true, you ought to be able to sue Apple for missing Wall Street's estimates. Tim Cook clearly isn't listening to his bosses and has stolen money from you as an investor who disregarded Apple's guidance and instead went with Wall Street's guidance.
For us, sure. I don't have time to get into the details of AAPL and why I may or may not want to buy them. I honestly don't have any idea if it's a good buy. However, it's 67% inst. owned and I'm willing to bet that every single instituion that owns stock has its own person who is crunching numbers and assesing value. The fact that the big spenders are fighting with each other to sell it instead of buy it means it's more than just "goofed" estimates.