Plan ahead, sure. I think implementing it should wait however. 1NXT is not that much and we already have people worrying about the distribution of NXT as it is. I would prefer to see it tied to volume and transaction total. Not to a fiat or even BTC price.
People don't think in terms of crypto prices yet, they tend to think in fiat terms.
When/if fiat currencies do collapse, then it'll make more sense to tie the fee to something else,
but now, even from the marketing standpoint, it sounds great when you say that the fee is only 10 cents, all people understand cents, fewer people understand exchange rates and how much it costs in crypto terms. But when you say 10 cents, everyone thinks - wow, so cheap, I gotta have a thorough look into this online currency.