@ why ...
I tend to suggest to look around and get a feel for what you want.
Or, I would profile the client to get a better understanding of what they are looking for.
The above depends on budget, goals and such.
In my current situation, I have trouble coming up with concepts for myself. wall of white ...
Strange that I don't normally have that problem with clients.
Anyway, I spent days and hours cleaning up opencart's templates and putting in a design that I wasn't satisfied.
I found themeforest the other day by accident even though, I have been to nuttuts several times.
I came up with a concept within 10 minutes. I really don't even like it!
BUT it grabbed my socks and I knew that this was what that site needed.
My other site took a bit more time about 3 hours of going through almost all of the templates and that was the site that I knew what I wanted, but ended up going with an older concept from 3 years ago.
So, I do agree that a "for sale, free" template does not know what you want. But sometimes you don't either or even if you do, you didn't know that you wanted something else.
@ letting a designer go at it ... (a bad experience)
When I built the bridal shop site I mentioned above, I had thrown together a concept, basic design, colors, storyboard, layout and had a designer come in and decide that they knew better. I ended up putting the design on and I'm embarrassed to even list it in my portfolio. That shop had "supposed" talent and skill.
So, after a few bad experiences like that I now tend to tell people to "check out" what's on the net. They can always go from there knowing that they can ask for a designer and/or coder to assist them in their needs.
@ unique design ...
Interesting point. I don't know what you have produced but a shopping cart is to some extent limited in layout and design. Xsecrets did post a link to site that was pretty radical but that is one of the rare ones I have seen. Even 37signals (founders of Ruby on Rails) used to do excellent and exciting work but then everybody copied them in some for or another... unique.
Or you go the other way and make it so unique, nobody can figure it out.
However, if you are talking about the other unique that is based off the client's profile then, obviously, I am in all agreement.
I'd be interested to see what you feel is unique since I could obviously be wrong in my thoughts.