I would agree with you, but on the other hand, it makes getting further away from the attacking ship a motivation. Besides, if both sides have the bonus, it kind of evens out, just making closer combat more dangerous. That's probably why there wasn't range modifiers (to my knowledge) in the original Traveller. Besides, wouldn't up close with a meson gun be more dangerous than far away?
I'm making the closer ranges positive in my book. We'll see how it goes.