Compared to facet-based engines?

Given how powerful facet-based engines (Faceted Search module, Solr, Sphinx) have become and how easy they make the search process, for a site that has no business *requirement* to use it, is there really a reason to use the Google engine beyond simple name recognition ("Oh, they search their site using Google, so these results must be authoritative)? I'm not looking to start an argument, just looking for thoughts for/against. Thanks.