Not in my experience. I've always got some response/acknowledgement/PFO any time I've applied for a job.
That doesn't mean that its the same for anyone else, or that the credit crunch has changed how people reply to applications. The number of posts from people getting no replies would tend suggest its very common even the norm anyway.
Wrong. It has value for both the applicant and the employer. It tells the applicant that the application has been received and declined. No doubt, no wondering. It brings clarity. For the employer, it reduces the likelihood of further queries, particularly if it gives some explanation as to why it was declined.
Wrong yourself. Your not going to get an explanation in automated reply, or spending 2-3 seconds per email as you suggested previously. People who aren't happy with no reply, aren't going to satisfied with an automated reply either. Getting a reply might even encourage them to look for more feedback.
That said it not that useful to generalise as every application is different.