EDIT: If someone follows the trace in the explorer, he can see where it went and so he can see how much I have anyways, right?
Not with change address.
Imagine this scenario. You are paying address A and you generate a transaction using Electrum.
Electrum creates a transaction with the following as output:
Address A - 0.2BTC
Address B(change address) - 0.3BTC.
Anyone who sees the transaction won't know how much the sender has since they have no way to know whether the sender controls either of the address. Of course they can estimate, but with very low certainty as opposed to sending the change to yourself.