Many affiliate program offer turnkey i.e. provide the template and content so all you have to get is just a domain and hosting and then just upload the template and content to your domain and your site is up and running. But I do not see many affiliates using such turnkey. Instead many affiliates create and design their own unique website and then just embed in their affiliate links. Why do they prefer to create and design their own unique site? Customers usually will not be able to differentiate between turnkey or unique website so why bother creating own unique website? For Better SEO?
This is the norm. If they use the premade template then their site will be same with other people site which mean is unprofessional. The image of site is really important coz it can attract buyer.
the turnkey sites are there for newbies. Since many of them don't have clue on how to build a website. On the other hand building a website can be expensive for them as well. People look for opportunities online most likely they don't have a lot money so this turnkey affiliate programs offers a platform for them.
unique is the best way, the turnkey sites usually have teh same old design that alot of the e-book sites have and most people just click close when they see them. also the content tends to be the same as everywhere else on the web so its not really getting priority.
It might be an issue of control. Whether or not the site owner is able to make changes easily on the website. Most people want to put their personal stamp on a site. Also, if your trying to brand yourself, you have to be able to stand out.