I think you miss to address the biggest, if not the only reason, why you should still do press releases. The reason is called "Google".
You do a PR to get noticed and to eventually drive traffic to your site. (If you have other reasons, it is probably waste of money). Doing a PR will get you in the Google news section, which will help you get indexed and most likely improve your overall ratings (again - Google). So, PR is very useful to get the backlinks from reputable sources, which will improve your index with Google, which will help you get closer to top search results, which will potentially bring more visitors to your site.
If you include in your PR a link to a landing page (hint- you must!), it will be much better, because it will help you track visitors and make an offer or collect an email address with a lead magnet offer. Never send a customer to a generic Home page. You will lose her and will be only paying for consumed bandwidth and PR fees.
So, there you have it. Now go ahead and implement the quick marketing tip I just gave you here and you will realize that PR still has legs.