Some things need to be opt in but most things don't. What makes sense to have which way is not as simple as saying "if people wanted it, they'd configure it that way". Imagine how many problems having to opt in to keeping recent files or whatever on each program you use on all of your devices would be. Apart from the annoyance of setting it up, the annoyance of forgetting to set that (among a dozen other opt-ins) on one of your dozens of programs and finding out only when you can't remember the name of the document you had open yesterday. Most people would "opt in" to use a provider which has what most consider "sane" defaults instead.

But there are obviously MANY things we prefer to keep opt-in. E.g. sharing my recents data with 3rd party advertises. No need to throw the baby out with the bath water and make every service awful by default just to have a universal rule to quote though.