Im no military planner so Im not gonna get invested in this debate haha - and obviously a human death is a huge loss - but presumably you could drop a lot of bombs for each lost fighter, so the bang/buck (literally) would be better than with missiles.
Planes aircrew high fixed/operating cost - lower unit costs on strikes.
Missiles, more expensive - depending on.
Missiles are not 'rocket science' - pun intended. They're expensive because of the overhead of military industrial complex.
Russia is making ballistic missiles 'China style' - super fast, super cheap. Basically - much bigger than ATACMs, longer range, a bit less precise but vicious. Similar to Iran.