There's plenty of reasons to secure all communication as much as possible, regardless of the content.
Even if you don't care about what your ISP sees from a privacy standpoint, they still can inject ads or other content into your webpages if the connection isn't secured (at least, from the perspective of your ISP). And this helps prevent attacks against users in coffee shops or other public, unsecured WiFi.
Even if you don't care about what your ISP sees from a privacy standpoint, they still can inject ads or other content into your webpages if the connection isn't secured (at least, from the perspective of your ISP). And this helps prevent attacks against users in coffee shops or other public, unsecured WiFi.