The problem is that email is not guaranteed to arrive in 30 seconds. Speaking from experience, it is extremely frustrating trying to access a resource and being unable to do so because someone in the entire email chain did a transient whoopsie.
Yep. And it's often not solvable by just sending the email again: I've more than once found cases where an app's email provider is particularly slow and the tokens arrive late no matter how many times I send them.
Bonus points if each email has a new token and only the most recent one is valid, because then you're stuck trying to remember how many times you clicked the "email me" button. Is this the right token, or am I waiting for one more to come in?
