So then isn't it a better practice to just store all your data onchain to have access to it?

It will be more expensive. You will always have to consider what you want to achieve. If its data that isn't needed in the smart contracts it would be a waste to store it onchain. If you need it in the smart contracts you will have to store it directly in the attributes. And if you have information that will be used in both your smart contracts and on stuff like marketplaces it might be a good idea to store it multiple times ?