David was recounting the events of the Exodus, so I'll say it was for travel. I'll stick to the word of God when it says no one was feeble, no one was feeble (aka weak). Nope, I never heard that.
It would be worth your while to look into it. It will change the whole perspective.
Yes it was for travel which is my point. It was not that they were prosperous but fit to leave. If you will remember they had been hard pressed to make bricks and to finish the work that had begun. Pharoh had been making everything physical for them.
I always stick with the Word of God. I don't know anything else.