This is something that has bothered me a lot recently, and I question whether it's good UX design or not. I'm not a huge Twitter user and very rarely log into the service. However, I sometimes am curious what the general consensus is on a particular hot topic, or if something of local significance is being talked about on the site. As such, I like to search Twitter now and again to see where people's opinion's lie. However, I don't see anywhere on the site's main page a search option, nor any links that get you to such an option. Granted, if you are signed into the service, a search box is clearly present at the top of the screen. However, I'm curious if this design of requiring you to log in first ultimately hurts the user experience?
I know you can go directly to http://twitter.com/search to get to a search box without logging in, but I really don't understand why they don't link to that on their main page. Are there good reasons from a UX perspective as to why you would do that?