Indeed the target market is of importance, however I do believe that any business has to keep up-to-date with the latest trends, especially in such technology-based businesses like webhosting.
The numbers don't lie - the usage of mobile phones is growing each year, online shopping through mobile devices is growing, heck, even Google based their latest algorithm changes on mobile and voice searches. And with each new generation, our phones become more and more our computers and have the full capabilities to do so.
In my mind, a responsive design of a website should not be a fancy luxury nowadays, it should be a logical next step in the development and improvement of any business that decided to operate online. :rolleyes2