People will just farm for this stuff and get the upper hand on other players who don't play as much (not like they don't have the upper hand on those players already, right?), the whole game will be a mess with this "Kill 1000 of this enemy for this reward". If someone were to manage to get enough of these bonuses stacked it would be heavily imbalanced. And don't think that there's no one with enough time to do this stuff, people's lives are being devoured by the FOnline addiction as we speak.
How exactly would this suggestion work - logically? If I killed 1000 men in real life would I suddenly be better at Science, First Aid and Doctoring? It's a disguised excuse for HARDCORE (the guys who have enough time to grind 100k caps to pay for 100 reputation) players to get extras that the guys who don't play as much can't.
And that's what is called a constructive comment.
Yes you are right. The idea, if ever took into consideration, needs tunning. Even though killing 1k creatures is already extremely time consuming, there will always be freaks that will do that over and over to eventually become "immortal". In order to prevent it, the kill count, required to obtain a bonus, could be progressive (f.e. 1k, then 2k, 4k, 8k) or it could be just 1 time boost with no option to repeat it. I'd say that rewards should be only for killing high level creatures, like deathclaws or aliens, not for rats. Adding anything to important skills this way isn't relevant too, since it would mess up with character planning.
These are just adjustments though - I think that the idea itself, if implemented properly, could add a lot to the game.
EDIT: As for hardcore players.. no matter the game, they always have an advantage. But isn't it how it's supposed to be?