Yeah, I've made a habit of this too -- what is the _advantage_ for me in typing in, say, python.org when there's a risk I might be misremembering it as python.com?
I believe there's also a slight security advantage, in that search engines will index and respect redirects to HTTPS (even without HSTS), and if I click through the search engine link, I stay on SSL for the entire transaction since the search query itself is HTTPS. This protects me against a man-in-the-middle when possible, and also saves me the annoyance of getting an SSL error when not. (I am also training myself to type https:// instead of http://, but the search-engine route is way more usable.)
I believe there's also a slight security advantage, in that search engines will index and respect redirects to HTTPS (even without HSTS), and if I click through the search engine link, I stay on SSL for the entire transaction since the search query itself is HTTPS. This protects me against a man-in-the-middle when possible, and also saves me the annoyance of getting an SSL error when not. (I am also training myself to type https:// instead of http://, but the search-engine route is way more usable.)