I agree with you about time and when I take notes on one year's trip to the next (time to the spring, summit, trail junction), it is either spot on or off by a constant multipler based on my conditioning or companions that year.
The other way I stress time if for that stupid question you get all the time, "How much further is it?" which is always from a newbie. Even if I know it is 2.8 miles, what does that tell them? But I'll note my own times and tell them "It took me 40 minutes from here, but I hike pretty fast without stops, so maybe 60-70 minutes to go." (having eyeballed their physiques and hiking speed as we approach each other) or "You've done 70% of the vertical since the trailhead, you have 1,500 vertical feet to go." Especially in the Sierra, Whites, Cascades, etc, we can slowly educate other hikers about vertical trumping horizontal by using these more useful perspectives in our conversations with them.