The problem with fees like this is that they're either trivial - 10 credits a module a day, or something, so even if you leave a full module storage alone for a year you're only down a few million - and therefore not really worth implementing ... or they're substantial enough to be noticeable and therefore don't fit well with the wide variety of earning rates out there. A million a day in storage fees would be mildly inconvenient to me, absolutely nothing to a core miner, and a serious challenge for semi-casual players.
They also wouldn't fit well with exploration - if someone goes on a six month trip, they're logging in every day (so they don't get any cheaper/no rates for that), and they're doing stuff which will at some future point earn money, but unlike the other professions that money isn't going steadily onto their balance - it all goes on at the final sale.