Correlation is different from cause.

<meta> tags are not useless. <meta> keywords is useless, but <meta> description, date, author, content-type, and many more are useful.

In particular, <meta> description can be used to increase the chance of someone following the link to your site, after finding it on Google.

Note that there is much controversy over the use of <meta> keywords. I believe it's useless, but many others disagree. Of course, they're all wrong.