Im curious, what exactly don't you like about the existing exchanges, which do allow both way transfer of BTC into and from USD or EUR?
As for exchange rates fluctuation, if I would offer services or goods for Bitcoins, I would like the exchange rates to fluctuate as much as possible. And under no circumstance sell into USD directly when receiving Bitcoin payments.
Let me elaborate on that, using the example of Switzerlands CHF vs EUR. The CHF is historically a panic security currency, similar to people banking gold or bonds instead of shares. So currency traders go to the Swiss Frank in times of down markets.
More then 50% of real world product and services geared towards foreign markets in Switzerland are going to the Eurozone. That means that in time of a downwards market, exporting stuff gets increasingly harder, due to exchange rate differences. Now the main problem with that is long term agreements on prices, because that makes the sellers a victim of the exchange rate fluctuation. As competitors to EU markets, there's no way to define the exchange rate willy nilly for these contracts.
But the situation is actually much different for BTC and the high fluctuations. Assuming I'd be a seller on the internet, using Bitcoins or USD. If I would make a Bitcoin price, it would make sense to overvalue it. For example, the current conversion is about 20 USD for 1 BTC. If my Product costs 20 USD, the BTC price should be 25 USD when converted right now. Three days ago the conversion was about 30, so i'd price at about 37 USD. With this security cushion, I can easily hold on to my money, even if Bitcoin goes down on the exchanges. Due to the huge fluctuation in the market, within a week or less, I can achieve a conversion rate of better then the already inflated price that I did demanded from my customer. Sometimes I might need to sell my Bitcoins into Dollars for less then 20, but most often I won't. At least as long as Bitcoin continues to work.
Now one could argue that this is an unfair profiteering on the back of people who want to pay with Bitcoins. But as BTC is a very new thing, compared to other monetary payments, payments made with it need to include a risk payment of sorts. This situation is comparable to how PayPal started. It used to be very new, and offer much better rates then using a Credit Card directly, in additon to gains in convenience (mostly for the seller). These days, Paypal actually costs more then most other third party CC services, and is a pain to use as a seller, and incurs increased callback risks. But that doesn't matter, because it's well established.