This is one I never could figure out either. They have several coins I've never even heard of, but not DASH. I used to think they were scared of the privacy-centric nature of DASH, but since they've added Zcoin, I can only assume they have some personal animus against us. Does anybody have any idea what it could be?
It just doesn't make any sense...
Common sense tells me that exchanges generally don't care about distribution, "fairness" or developer intentions. They are interested in 2 things: trading volume and security. So if the trading fees are worth the trouble of adding another asset and if it doesn't compromise security they should do it.
Historically, Dash has had the lowest trading volume of all top 10 alts so this might be the cause. I suppose the recent BTC-e listing happened because they expected some kind of high-volume action to happen soon. But seems like they were wrong and another coin was pumped (and dumped) instead.
See, you're exactly right with respect to what you'd *think* would happen. But let's look at what actually has happened:
Kraken trades Stellar Lumens, with $76,000 total volume daily
Kraken trades Iconomi, with $191,000 total volume daily
Kraken trades Augur, with $450,000 total volume daily
Kraken DOES NOT TRADE Dash, with $1,100,000 total volume daily
Granted, I'm using the last 24 hours' trade volume as my "total volume daily" measurement, but it should be good enough for my purposes. Dash has a trading volume up to FIFTEEN TIMES GREATER than some of the alts Kraken trades.
The decision to incorporate those alts and not Dash is economically irrational, which means there must be something outside of economics at play here.
(Bitfinex is similar, with several low-volume alts but no Dash. They delisted us and then added coins with a fraction of our daily volume.)