It is still worth to use bitcoins because the value has increased and satoshi's will still be on the same track. Before you are thinking that 0.005 BTC is still a cheap amount of bitcoin but right now the price is high and you may think it's gold and you can now reduce it to lower amount. But if you don't want to do this, you can just simply use alt coins.
I can see no point in using other altcoins. As you said yourself we can reduce our bets to lower amounts in BTC. Using other altcoins may arise confusion since we are used to BTC, I rather wouldn't do that.
There's no confusion if a gambler decided to use alt coins. Since the casino's are accepting alt coins for now there's no confusion with it. And if you think that it's not worth to spend bitcoins for your bets then don't bet with it. Just bet with what you feel what is better.