Jenna, everyone could get along so well if people were just honest with themselves about what they're doing and what they are learning. (I say that and chuckle, because I'm picturing the TMA guys thinking about the BJJ/MMA guys, and vice versa.
Another thing that makes me chuckle is the sexual tension between Hanzou and jobo. (just kidding, guys!)
Your analogy is a good one. To stay with it for a bit longer, I see it like a carpenter sees a guy waving a screwdriver around in the air, in a hammering motion. .
Carpenter: "Hey, what are you up to?"
Other guy: "I'm learning to hammer nails into wood with a screwdriver."
Carpenter: "That's... kind of the hard way. If your goal is to drive nails into wood well, you'd be much better off using a tool made for that. And maybe get some nails... and a piece of wood."
The other guys says, "No thanks. It's really not about trying to drive a nail into wood. I'm trying to learn life lessons."
Carpenter: "Well, oookay. So, you don't really care about actually being able to drive nails into wood. That's good, because it seems like a very hard way to go about it, and I don't think you'll ever succeed. But, you may learn some life lessons, and if it works for you, great."
Other guy: "AND, I will eventually become very good at driving nails into wood with my screwdriver. It's the art of carpentry, and after many years, I will be better at driving nails into wood than you."
That's where we run into problems around here all the time. That last statement. We see it all the time. Look at the kerfuffle over in the MMA vs Tai Chi thread for a recent example. It's a mess.
It's very simple. You can approach your training in one of two ways. You are either training in something you enjoy, and aren't overly concerned with results. This is perfectly valid. I like BJJ, and don't really worry too much about whether it's going to help me defeat 10 ninja in a dark alley. If you're training aikido and like it, or are swinging a screwdriver around in the air, knock yourself out.
Or you can approach it from the position of wanting to achieve certain goals, whether that's wellness, effective "self defense", fitness or whatever. And in those cases, the goal will (should) drive the choice of activity.
Either way, you're only learning what you're actually doing. If you're swinging the screwdriver in the air, that's the skill you're improving. You're not learning to drive nails into wood, you're learning to swing a screwdriver in the air.