The notion of "cheating" the contribution graph is senseless, because it's not a competition. However, what it was great for was motivation to yourself to write code (however minor) every day.
I used the streak count to help push myself to keep working on a project I would've otherwise quickly set aside. My last streak was 27 days. I found when I broke a streak, my motivation to commit was much lower, and I would let my project lie for several days at a time.