I hope to see primedice accepting altcoins soon.
It would be a big boost for both the altcoin and primedice if Primedice could let people bet with altcoins.
It wouldn't bring too much new customers imho, since every altcoin holder/user also uses bitcoins on a regular basis, and the hassle doubles will each new altcoin that would be added.
To those that can and have the time and resources, it would bring some small increase in traffic, but i just don't think it's worth it, profit-related.
This is my take as well. It is always great to support new payment systems, and indeed new people will use them -- sometimes however you have to know where to draw the line and invest resources elsewhere.