I don't know whether it's sites that add outgoing e-mails to a backed-up queue, or if it's an anti-spam heuristic somewhere adding the delay, or delay on the servers of your own webmail service, or whatever combination of these, but unfortunately it's certainly not always as simple as "switch to your email app, click the link".
Fundamentally the solution to all this is that you should have a signin at least once (to get your identifier keys securely) but then every website should authenticate against your keys, not against a username and password, and it should be transparent so as long as you are logged into an "account" you have personal keys for that identity that correspond to all the other services you use.
Really, its how the desktop works, and it is how the web should work, since they are converging and all.
What et1337 means is that you never even create a password, you literally login by putting just your email in, switching to your email, and clicking the link provided.
Given that most sites require you to do this when you first create an account to prove you own the email anyway, what was the point of having a password?