It's really spooky to do that, John. Live Journal recently gives a really good example of why. From http://news.livejournal.com/114123.html (in part)...
Recently some journals and communities have been broken into, their contents deleted, and their owners locked out. Hotmail recycles email addresses that haven't been used in more than a year. If you validated a Hotmail address for your journal and displayed it publicly in the past, but then let the address lapse, someone who finds and re-registers that address can use it to obtain control of the journal.
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All someone has to do to change a password at Adobe is to send for a "forgot my password" email then click a link in it, and presto... as long as they have control of that email addy, they have control of those product registrations.
No idea if it's just hotmail... could be virtually any domain that recycles addresses or is resold also... if they aren't going to allow people to change the addy that controls accounts, Adobe is putting customers at risk.
If they are going to do that, they really should force at least an answer to a secret question from people... and if they don't know the answer, they'll have to call customer service who will attempt to confirm their identity.