Earlier quoted context omitted.
Why do we build foundations for the structures that we build?
We do that when it's necessary for stability of the structure, not as a goal to itself. What is strength useful for? (and yes, this is a rephrase of the previous question because of your non-answer)
Here's a practical one, not being winded at the top of the stairs. I work on the 3rd floor of a building. There's one elevator, it's painfully slow. Most people take the stairs. Every day people pass by my cubicle (near the entrance) winded from their walk across the parking lot and up the stairs. That's pathetic (having been there myself a couple years back, it's depressing too).
Have or want children? Wouldn't it be cool to be able to play with them for more than 10 minutes before feeling exhausted? Or to be able to carry them in from the car when they've passed out (or pretended to be asleep), even when they're older than 2 or 3?
Ever find your home office has filled with clutter and wanted to clean it out? Being able to carry out a box of trash or recyclables or giveaway stuffs without needing to stop every 10' or carry one item at a time is nice.
EDIT: I'm not in great shape, that's been my state for 10 years now. I am, however, in better shape now than most of that decade. Beyond the practical uses of this physical condition, it's helped me out in a number of other ways. I'm more alert. I sleep better (those two are, of course, related). I'm more attractive (hey, no more double chin!) which also helps with self-esteem. My mood is generally better (if you read my post history you'll find a history of depression, I won't say fitness has eliminated it, but it certainly is helping for me).
Back to (somewhat) practical uses of better strength. I'm able to help friends with tasks around their homes instead of trying to come up with excuses to avoid it (because I was, for a time, more of a drag in those cases than a help). I can go play laser tag without collapsing at the end (4 years ago, it was embarrassing). Bowling, not the most demanding of games, no longer exhausts my arms (I bowl both left and right handed).