There are a lot of questions tagged with amazon-ec2 or amazon-aws that seem completely irrelevant to EC2, they're generic questions regarding servers that just happen to be running on EC2, quite a few of them could replace EC2 with 'Rackspace' or 'Softlayer' or 'Whatever Provider Inc.' and the question would still be the same, is it appropriate to un-tag these questions?
Sometimes questions are tagged with ubuntu or centos even though they have nothing to do with Ubuntu or CentOS. However, knowing which distribution the user is using allows the answer to contain distro-specific instructions like using apt-get instead of yum and /etc/apache2/ instead of /etc/httpd/.
The Amazon-related tags could allow the answer to contain Amazon-specific instructions in the same way.
If the tag has zero relevance to the question feel free to remove the tag (and/or add more appropriate ones).
Unfortunately (and especially for new users) tagging is more of a "Throw everything at the question and pray someone sees it" than a surgical "I've isolated the problem to these items" kind of thing. Fixing lousy tagging is definitely a Good Thing.