I certainly don’t use and would never use Strava Premium, but I wouldn’t want to go without the site as a whole.
I love being able to follow pros on training camps, sometimes with power data (I’ve stolen interval sessions off Robert Gesink and I’m now following with interest Harry Tanfield’s first winter as a pro tour rider).
I like finding riders from areas where I’m going on holiday and using their rides to plan my routes there.
I can see what rides my clubmates are doing and if their photos look good, save that route to ride another day. I like that new club members can follow me on Strava and pinch my routes, too. And I can see how team-mates got on in races and TTs.
I can look at how the top TTers paced the TT course I’m going to be racing that weekend and pick up tips that way.
And I like to see how I compare with (a) clubmates and (b) me from previous seasons on my starred segments.
Loads of reasons to use it still.