EJ,
I have been designing a Formula 1 racer for a few years now. The project has been on hold for about a year and a half. Regardless, I used Solidedge 2D to do the preliminary drawings. 2D has some application, in that you can accurately draw airfoil shapes with all the compound curves, etc., and still keep them symetrical and smooth. Further, the ability to quickly compute areas of the wing, fuselage, etc. are very helpful, so that you can plug them into various performance formulas. That being said, 3D CAD is superior, and offers some really big advantages. Drag approximations are always a big part of the performance analysis while the aircraft is in design stage, and given the past use of 2D images to derive a 3D area, the drag numbers arrived at can be imprecise at best. 3D CAD can give you accurate values for wetted area, especially when using the cutting-edge, compound shapes you see in aircraft today.
I could go on, but I'll stop and say that ultimately, 2D CAD was a big improvement over the older, manual methods. 3D CAD makes 2D look almost as outdated 2D CAD did to the drafting table.