I have a question on framing techniques for an exterior wall. I know that the typical method is to lay down the sub floor, then frame the exterior walls over the sub floor.

Is there a down side to framing an exterior wall directly on top the joists and rim joist(adding blocking were necessary), and then lay down the sub floor butted up against the bottom wall plate?

I am in the very early planning stages of putting a new laundry room on our house (~10'x10'), it will have very limited access under the floor (~1'-2' craw space). I would like to get the exterior walls and roof up as quick as possible, then take my time to rough in the plumbing and insulate, and it would be a lot easier without the subfloor down. One option I was debating was to lay the subfloor, frame, then cut out what ever area I needed to get access to, but this seemed like a waste.

Any thoughts?