they can bet in bigger number of doges but that will only make the game slower if their goal is to play for profit because like you said , the value of doge is verry low but doge is a good coin choice when playing for fun only .
doge coin is also a good coin for those who dont like waiting when depositing because its a lite/light altcoin which is fast compare to btc and other heavier alts like eth . gl to roobet casino . hope they can catch up on the competitive market of gambling .
Human tend to prefer to own more, more coins and yes, quantity makes sense for most of us. With the same value of coins if we cash out into fiat, I think most of us would prefer to see bigger amount of coins in Dogecoin, in millions, rather than some Ethereum coins. It is basic preference of human.
Moreover, there is - at least - another reason why Dogecoin is a favorite one for casinos. I have never heard or read somewhere that Dogecoin network has congestion issues. I could miss something and I could be wrong but from my knowledge and my three years in crypto market, I have never heard congestions on Dogecoin network. It is good to use on casinos.