I find this problem with a lot of bags, I have a Topeak one that conveniently allows the head tube and down tube straps to be removed, and therefore replaced by something better (double sided velcro roll) but the top tube straps are huge and not v flexible so wrapping round a steel frame gives pretty shit results
Yes if they had separate straps through a molle type loop that would be much better. Building to a price I guess. The handlebar bag I ordered did have separate straps however. I'll see how the lifeline ones are and report back.
I find this problem with a lot of bags, I have a Topeak one that conveniently allows the head tube and down tube straps to be removed, and therefore replaced by something better (double sided velcro roll) but the top tube straps are huge and not v flexible so wrapping round a steel frame gives pretty shit results