I partially agree with you. I agree on that XCP and BTC are bad units of accounts. I'll also add that Counterparty is a platform where anyone can issue / invent a better currency, e.g. a trustworthy company can issue a counterparty-asset backed by the dollar. Then it's up to the free market (i.e. users of counterparty) to decide on their preferred choice of currency. At the moment XCP and BTC are the least worst, hence chosen by the market.
The problem with "inverse" prices, however, is merely a psychological one. In real life we buy a Snickers bar for price $2 at the supermarket, right? It's equally to correct to say that we sell dollars for price 0.5 Snicker at the supermarket... Next time you enter a store, tell the clerk you have some dollars you want to sell
In the Counterwallet I suggest just that when XCP or BTC are part of a trade, these will be assumed as currency (no change needed in Counterparty itself). There might be some more elegant way of dealing with the problem. E.g. by counting how many different token each token has been traded against. The higher count, the more likely it is to be the "currency".
Just to clear up confusion, Counterwallet uses Forex currency pair naming (see http://www.investopedia.com/terms/c/currencypair.asp). The rule system we employ with which currency is the base currency, and which is the quote, is as follows:
* If XCP is either one of the two assets, then XCP is the base currency
* Otherwise, if BTC is either one of the two assets, then BTC is the base currency
* Otherwise, the base currency is the currency whose name comes first, alphabetically
So we do have a system in place, but I can understand how this is still confusing to people (and to be honest, forex currency pair conventions are definitely counter-intuitive...I had the same issue with them as well). To me, it seems that the exact convention used in Bitcoin-space can be inconsistent. You have sites like BTC-e.com, which seem to use this same Forex convention, and then you have sites like Poloniex, which at one point months ago seemed to use the inverse, but now also seem to be on this same forex currency pair system. So, as far as the XCP/BTC type syntax, on second thought I'm not 100% sure where the confusion lies, as it's the same convention many/most of the BTC exchanges use.
However, regarding the buy/sell interface itself, I can understand people's objections, specifically that it's a) not what they're used to with regular BTC exchanges and b) that the interface can be confusing in some regards. As a response to this, I did put together some proposed tweaks to our trading interface that I'm thinking may help make the interface more user friendly (but I could be wrong, or may have missed something). User input is welcome. Please feel free to comment on the github issue here: https://github.com/CounterpartyXCP/counterwallet/issues/238