Here are some advantages of building a custom WordPress website as opposed to using an off the shelf WordPress Template.
Pre-built templates are developed by several different developers so there will be very low consistency with how themes are structured and coded. Everything from HTML, CSS, and naming conventions to functions will vary massively which can often make even simple tasks such as tweaking a column width an overly timing process. This alone is a reason to develop a bespoke theme as it will save you plenty of time in the long run.
2. Creating something unique
With a template you could end up with a great looking website, however, if it looks like a clone of thousands of other websites out there, it will most certainly get lost amongst the noise. WordPress drives nearly 20% of the web, and if you have a website that looks no different to several others; people will be less impressed and also less likely to come back to you. Creating a bespoke theme gives you the opportunity to create something different that looks exactly how you want it.
3. Faster Development
Building a bespoke website will allow you to develop a website with SEO in mind. The website will be developed in a very consistent way, in terms of HTML, CSS, naming conventions. It will definitely save you time in the long run as any updates or additions to your WordPress theme would be much easier as we would already know which CSS styles to modify or function that needs to be modified before making the change.
4. Only using features your project needs
With the majority of the theme templates on the market, they come packed with options to customise your WordPress site. Most of them will not be used, adding unnecessary files, styles and bloat potential processing. Developing a theme from scratch means that you will only have functions, styles, files and structure the website needs. This will keep the website clearer and cleaner.
5. Increased speed
Website speed is incredibly important. Search engines are beginning to penalise slow websites. An off the shelf theme is packed with unnecessary code and functions. A lot of themes have several different theme templates built into one Theme so you can only imagine how this is going to affect the performance.
6. Less reliance on plugins
A great feature of WordPress is the availability of plugins, however this makes it too easy for users to use a plugin for even the most basic of tasks. Theme templates come overloaded with plugins and overtime you will end up spending a lot of time wondering why plugin A is not working with plugin B. In a custom built theme, very few WordPress plugins are used as these are hand coded and built for your website. So not only is maintaining the code a lot easier, but the website will only be using functions that are needed for the website.
7. Updating the website
With a bespoke website, the backend of the website will be a lot clearer and easier to update. Each page of the website will have custom editing tools for specific pages. A template would have a very generic editing tools where the user would still need to know some HTML and CSS to be able to change a page or even more importantly, update a page without breaking the themes structure.