I see agnosticism as a truism and a starting point that tempers the way you see the world. It's important because it keeps us grounded in the ultimate realty, but it's meaningless beyond that.
In other words, I think the reason most people don't think about it much, is because it is a self reinforcing truism which does not provide much external benefit; it doesn't teach us anything other than the fact that you can not know anything for certain. You could dwell on that for eternity if you wanted, and it would never teach you anything new. Once you've got it, you just put it in your back pocket and continue to explore life with the only tools available to you.
It's like if an omniscient being said to you one day, "Pssst, you're an idiot". And you knew it was true. So what? It's still all you've got to work with. So you recognize it and move on. So what?