Lets remember, P3D was once ESP. ESP was by Microsoft and was a stripped down version of FSX. ESP was going to become non-existent, cancelled, and Lockheed Martin purchased ESP from MS. What you see now are the remnants of ESP. P3D has been evolving, now most of its code redone, and yes, they now have a new menu screen, but its not like FSX. FSX remember is for entertainment. P3D is hard core. Its not frilly, its functional. Its fast and smooth, boots up fast, has HDR and superb interior shadows, and a lot of other new features that FSX doesn't have.
One of the fall backs of FSX when it came out was that menu screen. It ate up so much memory that it took forever to bootup. It booted up the last flight you had, or the default (got all the scenery loaded, plane, etc) as well as activating all the aircraft files (panel and aircraft configs) which if you had 100+ planes, that was a huge amount of RAM resources as well. The list goes one. Some work arounds got some of that trimmed down, but it was still a resource monster, though it was pretty to look at.
We have a menu screen now for those that wanted one. Be happy.
It will evolve, Im sure. This did.