Every HTTP request I send to Slashdot contains my cookie, which contains my login credentials. When I do this over a public WiFi network, it's trivial for any passive member of the network to sniff it, as it is for any intermediary. Worse, because it uses AJAX stuff in the background, if I briefly connect to a malicious access point by accident, there's a good chance that it will immediately send that AP's proxy my credentials. I've been using this account for a decade or so. I don't want some random person to be able to hijack it so trivially.