I have read several results of a Google search, such as this nice question: Is type="text/css" necessary in a <link> tag?. However, I am currently going through some css3 (it's not that new) code and I see text/css everywhere.
Has something changed, or this is just an old habit that we (the young people) should not inherit?
Nothing changed, it is used for backward compability and will probably appear more rarely with time, as more installed browser will support HTML5.