With the evolution of the web hosting services it has become more and more affordable to host multiple different websites under their own domain names within a single account and to manage them all from one master Control Panel.
The multiple domain hosting service offers centralized website and domain name management options, tools for complete DNS management, DNS forwarding, ease of use and extreme convenience in controlling your overall multi-sided online presence.
Also, with a multiple domain hosting solution you are able to use a parked domains service which enables you to secure a given domain for the purposes of a future project of yours, for web traffic redirection or for sales purposes.
If your goal is to make full use of what the Web has to offer, expanding your online presence over time, you will definitely need to get a multi domain hosting solution.
You will not need to bother managing separate accounts for your sites, domains and emails, since you have them all merged into one single account with this service.