I assume it's cost saving. From what I read, it supports the panel's native resolution, and one quarter of that only. Which means the scaling circutry is a non issue. The 2405fpw will accept just about any resolution and scale it to fit or stretch or display it natively. Dell knows how much that circuitry costs, and probably knows how much we'd be willing to pay for it.
If I was buying a computer monitor, it'd be a non issue. However, I bought my 2405fpw as a TV and a monitor, and was hopeing the 3007 would be a drop in replacement when the time came.
Matthew