Yes, scrambling is too strong. Yes, there should be a limit to number of ground units and air units that can be stationed on postage stamp islands.
I saw someone else’s game where the allies had built an airbase on Java and had about 10 fighters there. I don’t think it’s always as simple as just “going around them”. That move pretty much guaranteed this player that Japan would be out about 9 IPC’s per turn and could never take that island without very great difficulty. This kind of a move should not be possible.
When I did my very first J1 and double checked the scramble rules, I was amazed. Why should an attacker have to have enough force at sea to have a high percentage chance against all island fighters, and also have to have enough force against all the same fighters on the defending island? It just doesn’t make sense. Fair for both sides, though.