Its subscription based because you cant have 2500 players in the same battle in p2p.
Its not simplistic in combat, the mechanics are more complex than Elite, your not shooting with a joystick but the mehcanics involved in combat are WAY more complex than Elite: armor, shield, remote repairs, 3 different types of electronic warfare, multiple ammo types, cynosural fields, warp disruptors, titans, carriers, dreadnoughts, cloaks, stealth bombers and thousands more..., its massive.
Elite needs to be simple so it can attract more types of people.
ED has more complex flight model (EvE looks at ships as vectors of their velocity), but EvE has way more complex damage calculations. Where ED is all about damage faloff and resistances on two layers, EvE has full scale of application attributes of two kinds. Where turrets use tracking and radial velocities to determine wether they even hit, then damage is being additionally calculated not only based on resistances and damage types, but also transversal velocity. Missiles on the other hand, has flight speed and flight velocity, and if it hits, it determines damage caused by a function of explosion radius, velocity and target ship radius and velocity. TiDi works because combat is basically rts.