Templates are great, don't get me wrong, but putting a WP site up with a template behind it is only very rudimentary development of a name. It depends what the aim of it is. I have currently running and being used by people (apart from my affy sites etc.) a Home Information Pack management system, a contract hire management system, a nutritional analysis website (public facing:
Food Calculator - Nutrition Information ) and others. But none use or would ever use any off the shelf templates, as they have been developed to cater for a specific set of requirements.
Your point about designer/developer are they the same now is an interesting one, as I have noticed a definite change in customer expectations. In the past, everyone went to the nice flash graphicy design agencies to get super whizzy looking sites. That seems to be changing to people who want lots of stuff behind the scenes and ask if I can get someone to do graphics etc. They seem to have realised that a great looking site (and some of the templates out there, and others I have seen on here look great) is only part of their vision, and if it is only skin-deep, then they are not going to make their new idea work.
So whereas some people saw SQL, patterns and practices, source management, sharepoint, n-tier systems, client server, security, parameter validation, web services as boring, BUT LOOK AT THIS PHOTOSHOP MOCKUP!!! Others have kept going on the more techy side. I think web design agencies that have skilled up in the last few years should carry on OK. The purely graphical ones will suffer more on the web side of things.
But my current project which uses .Net / c# / sql for the techy backend stuff and then Word Press for the presentation layer gives me the best of both worlds, as I can use funky templates to display my info that was generated and gleaned using the best tools I have available to me.