From the Hotmail team:
"Really quickly, want to address the IMAP questions that have come up.<p><pre><code> We haven't implemented imap since based on the user feedback and usage data, there isn't a large enough need when you look at the other protocols we provide. for mobile - we believe activesync is the best story. it gives you mail, calendar, and contacts. there is big adoption of the protocol here with android, iphone, and windows mobile. for clients - with the outlook connector, windows live mail client, and pop3, we cover the majority of client scenarios. there are definitely some gaps, but not enough to outweigh the cost. one of the tough trade offs we make. let me know if that doesn't answer the question. -ryan"
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Either their user base doesn't know any better (likely) or they have an extremely skewed view of the market (likely).