I think the only real drawback to the using the jeans as cutoffs is the weight of the denim. Even though Levis has made the 501 a lighter weight denim - along with almost all of their other lines - it's still a bit too heavy for shorts (for me).
For my summers here in Indiana, if it's hot enough for shorts then it's hot enough for lightweight material. This leaves out the vast majority of denim. Perhaps if there was some summer weight denim I'd go for it. As it stands, light weight denim is usually considered of lesser quality (an assumption that is usually justified). I'm under the impression that with the newer lightweight denim Levis is using, the crotch would give out quicker than the knees(?).
I'm sure I could get some great fades with the classic raw indigo and a lot of summer sweat, but this is one area where I'd rather go for function.
For me, my summer casual shorts are lightweight Bonobos cotton (no affiliation). Bonobos shorts on sale They're currently on sale/clearance.
My summer work shorts are Carhartts. If you're going for Carhartt work shorts, look around a bit, as they have different wights. I have the 7.5 oz weight, so they're not the most rugged, but as a lightweight work short, I've found none better. The bad side is that the Carhartt fit is rather large; if it fits you in the waist, it'll be huge in the seat and thighs. I currently have two pairs of these that I put in rotation for the summer heat: Carhartt 7.5 oz work shorts