vito_excalibur posted about "beginner's mind" as it applies to Aikido, and explained very eloquently that "beginner's mind" is overrated. I posted the following comment in response:
But here's what I think is good about beginner's mind: the thrill of gaining a completely new skill, feeling what might be called "romantic passion" for the new pursuit, feeling your brain fill up with knowledge, feeling your muscles click into new patterns. Waking up after a frustrating time struggling with a new skill and discovering that a bunch of stuff seeped in while you were asleep and now it's much easier.
Insofar as someone praises beginner's mind, perhaps they are in part praising that enthusiasm.
I feel so much thrill when I am learning something new that I tend to hop from one interest to another rather than settling down and learning the intermediate or advanced aspects, at times.