I dont see a need for ground objects or a German 2 seater. The Bristol is a fighter by design and definition, much like a Bf 110. Heavy fighter-bomber. Im ok with the Bristol being in the game but not happy with the way it is used in the arena. Some people do some pretty lame stuff in it.
I do not thimk adding planes would help the overall popularity, only for a few days. Most people will want to try the new bird so WWI will be popular for a week maximum. On the Nieuport 17 and S.E.5a, they both will be so out-classed against what we have now they would become Hangar Kings very quickly. The SPAD XIII would be the same way except for the speed demons that like to fly straight like iwlf and Ordy. The SPAD XIII would easily be the fastest in the arena if it was added today. But as I said, try to turn in a SPAD and your toast in .5 turns. So I see no need for those either. We have a mid-late war plane set in WWI, to go to early-mid (SPAD XIII, N-17, S.E.5a) would just be a waste in my opinion.
Although it would be great to see 20 different aircraft in the arena, it will never happen. So, IF we are only going to get 1 or 2 more we might as well add planes that will play a significant role. Therefore Albatros D.Va takes the cake (copyright Sukov).