My WW1 'wants':
1) More Royal Aircraft Factory products to fly: the SE5a, RE8, BE series and FE2b/d.
2) Two 'countrys' instead of the nonsensical three.
3) Realistic trench lines separated by no-man's-land.
4) Artillery, and spotting for it; it was the most effective aerial method of killing of the Great War and a fascinating skill to master. Art-obs aircraft like the RE8 provided good targets for the Jastas too.
5) Observation balloons (which some AHers are incorrectly calling 'barrage balloons').
6) More Hun aircraft types: the Albatros B, C and D-series, DFW C.V two-seater, Hannover CL.III and Pfalz D.III and D.XII. And a Zeppelin to grab for in my single-seat BE2c night-fighter.
7) An early-war planeset: Fokker Eindekker v. Airco DH2, Halberstadt D.II v. BE2c, etc.
Reckon that'll do for now - cheers!