OK, I'm no expert, but there are hundreds of articles out there on SEO and quite a few books. It seems to make sense (if you care) to read an article or two, ask questions of theme developers and get referrals. That's what I do already when I spend my money with someone. That said, I intend to use Hybrid myself which in version 0.7 leaves open SEO for plugins. That means I have to decide which plugins (or my own) will do the best job.

I certainly believe it can be counterproductive to write for SEO, but it makes sense to present what you write in a way that search engines will find it and readers will enjoy it when they do. Each site/business will have to decide what investment of time/resources is warranted for a potential increase in traffic from SEs, but at some point the marginal return from better content, outways the marginal return for theme tweaking.