Speculation.
Informed observation, I've seen how 110s are and are not used in the game.
110 would probably be a quite popular fighter plane if it had a little better performance,dive qualities, and/or didn't tend to depart so badly when wallowing around in the stall. But that is not the case.
Note, I'm not against adding the planes in question, I'm just pointing out that the stats here are deceptive.