Taking CryptoKitties as example, I'm sure it's possible to achieve the same concept of Crypto Collectable creating new kitties as Smart Contracts instead of using Tokens. Which would be the consequences of doing so? I'm looking for a technical anwser :)
UPDATE from the future: when I asked this question my journey on Ethereum/Solidity was just starting. The question as asked is wrong. As obvious as it might sound ERC-721 is a standard for writing contracts, not a token itself (so "ERC-721 token" is just wrong). What you can do is store "tokens" (or NFTs) in this kind of contracts.
What I really wanted to ask was:
Why should I store a non fungible token (eg: a CryptoKittie) inside a contract that follows the ERC-721 standard instead of creating and deploying a contract of my own for each token (just a simple contract that describes the token and its functionality).
Nowadays the answer seems obvious: compatibility and cost efficiency.