You are right about that one... more of a "glamour" metric than something very useful (like when longest streak equals current streak which is the case for our internal dashboard [1]). In this case you know you've been very consistent over that time period. We will probably remove that one soon.
We do believe that at least with our product this kind of information it will inspire more confidence in our users when we publicize this information more (vs. lots of products that end up stagnating over time).
Also great for just seeing activity in one place. GitHub's website is great, but not really geared to providing much of this information in one place.