updated the OP with your idea, since i think you both make a valid/good point, and makes more sense worthy of its own thread imo. I didn't want your brainstorming efforts being wasted & buried under tons of other comments so placed it in the OP so folks passing through this thread who like this idea will remember this in the future should the stars align & an opportunity for bringing any needed change to gameplay.
Awesome! We have very few people here who do that. Kudos to you!
And on the topic and how it evolved: i still dislike the small/medium/large split. It just feels artificial. If anything, i would even say that a ships mass might influence some things.
The higher the mass, the higher the FSD cooldown. I mean, it still is only the FDS cooldown. It won't affect people too much in regular play. Interdictions and emergency FSD shutdown due to smacking into a star or planet are the only things where this would really matter. Considering how much sturdier big ships can be, they'd still be at an advantage even if their high mass doubles the FSD cooldown, so i guess this could be acceptable.
At the same time, when considering that this is only on the FSD cooldown, i guess it's not really enough to make small ships attractive again. I've pondered a few other aspects where small ships could gain an advantage, but nothing i currently can come up with would really make sense without creating other huge problems for the game.
In the end the small ship problem boils down to the fact that medium ships by now can be engineered to have the flight characteristics which formerly were reserved to small ships, while large ships can poach in former medium ship performance area. At the same time they can pack much more firepower and durability. Small ships still have an agility advantage, but between stacking shields, stacking resists on shields and hull and carrying SCBs, the firepower of their few small and medium hardpoints is generally not adequate any more. (I am aware of a few extreme setups which still perform acceptable, but they are not enough to change the big picture. )
So as long as weapons scale the way they do and engineering remains as powerful as it is, i guess this suggestion still won't be the necessary "make small ships great again" change. But if it just helps new players getting out of trouble quicker (almost only new players fly small ships these days), while bigger ships have to rely on their powerful defenses a few seconds longer, i would consider that all fine.