The market will price in lost funds on its own. Perhaps removing this fee will help. It will make my life easier.
I think you're right. What you need to consider is if this rule overall makes Bitshares better or worse. Since the market WILL price in lost funds on its own, there is no reason to have it, and the rule is making Bitshares worse.
Bitshares needs to have as few restrictions on use as possible. The less restrictions, the more use cases it is opened up to. More utility = a better product = a larger and stronger network.
Bitshares should also be as easy to use as possible. Having to move my funds around to avoid a fee is just one more thing that I have to research, learn about, and deal with to own some form of bitshares. If there are enough small annoyances I just give up and use some easier form of money. In fact, that brings me to another point that Bitshares should be intuitive to use. With a good product, you just know how to use it. I shouldn't have to browse the internet for hours to figure out how to trade on the market, or what the shorting restrictions are, or how to find the right way to open an account without already having funds to register, etc. It should just be obvious. I understand some of these simplifications are probably in progress, but the point is still valid.