Speaking only for myself, I think I used random encounters in the past as a crutch to fill time. We were in HS or college, had all the time in the world, and I wanted to whittle a few more hp off the PCs before the real adventure.

Now that my group all have jobs, kids, etc, we have X time to play where X < what we want. Truly random encounters are gone. Anything I'd want them to accomplish is either a few rolls in a skill challenge or "being attacked by boxed text" and done.

I'm just getting to the point where my prep time and play time don't allow for a lot of the stuff that isn't really on-point. That, and I always feel like my games in past were horrible and always have to be better than I was. Lots of "random" stuff (encounters, dungeons, treasure) was on the list of things I felt needed to be removed from my games.