Yea when I first join bitshares I was frustrated with the lack of usd/btsx charts. Now that bitUSD has launch I can use that (just need a little more volume)
I agree that it is a bad idea to calculate a cost basis for alts in btc. Unless you are trading back and forth from alts to btc and not using USD at all.
I have been using it, and to me it makes sense to use BTC.... okay, it 'made' sense. Now I will be rethinking things. I still think BTC has a few more rallies to live through, though. If you look at BTC as a DAC, and you see it for what it was seen before the likes of Bitshares and other encumbents, it made sense to compare everything to it, as it has/had the best growth potential.
I heard Peter Venesses talk about 1st order vs 2nd order Stochastic dominance, and the importance of recognizing BTC as such. (sorry, I don't fully understand it)
The point was, that when looking at one's return of investment from "mining" bitcoins, you can't use USD, because you have to consider what the same initial investment in simple purchase of BTC would have attained. In the past, most would have done better just buying bitcoin, so it made sense to use BTC as "basis"
I am rethinking this myself at the moment, since Bitshares has so beautifully gotten rid of the need for mining... i hope