Running a small little research around here. For example, Bitcoin has (or will have) a total of 21 million coins, tops. Litecoin seems it will have up to 84 million coins, total.
In your opinion, when a new altcoin is created, how many coins is just too much? I have seen projects with like 10,000,000,000,000 coins. That looks almost like... a spam coin :/
The token supply is not really that important. But if it's too much, it will increase the chance for whales to easily manipulate that altcoin in the future. In addition, the oversupply of resources makes the values of the tokens lower and allows traders to hold more tokens.