Spoken like a true web designer :lol:
It doesn't matter if a template is similar to 10,000 others - if the content itself is unique then it is completely irrelevant.
You are going to be able to find a flexible enough Wordpress theme for a small business 99%+ of the time. And they're going to get far more bang for their buck going down this route with a custom logo, than hiring you to do a custom job.
A Woothemes site with a custom logo is going to look way more professional than anything you can churn out for £1000 and its going to be significantly cheaper too. Would you agree with that?
To a certain extent, yes I would agree with you, but most people wouldn't know what to do with a Wordpress theme or HTML website template once they purchased it, it doesn't just turn itself into a website, so they would probably need to hire a dev or someone with some dev experience anyway.
I will also give you an example of why I said what I said originaly, it was not just because I am a web dev/designer.
A local florist where I live is losing loads of business to another florists based hundreds of miles away, the local florist is on a Florist shopfront type CMS website, that loads of other florists use, they just 'change the logo and add some content'

, the other florist has there own website.
The other florist has cleverly created hundreds of other pages targeting all area's of the UK and optimsed their keywords, alt tags, titles, the URL's are also nice and freindly.
I took a look at the local florist CMS and you can hardly edit anything, you cant add alt tags, you cant add custom text to category pages, the URL's are all rubish numeric meaningless URL's, you cant create custom content.
This is the issue with alot of these DIY template sites, a savvy SEO aware company from outside your area can easily outrank your site, I see this as an issue don't you?