The features offered in it (including fantastico) are so convenient that it makes installing php software a breeze; literally it takes less than 2 minutes to install a full working version of phpnuke or any other add on of this sort.
DH does not sell itself as an easy-to-use web host for beginners. They pretty clearly cater to the more technically knowledgeable; for example, people who don't balk at installing these types of web applications for themselves. This is ok, there's room for both types of hosting companies. This appeals to me, as I appreciate being able to do things myself, but I'll be the first to admit it won't work for everyone.
On top of that, cpanel comes with a huge amount of features that I’ve listed below.
Aside from automated installers, I don't see many things in that list that DH doesn't provide through their own control panel. A web-based file manager is the only big thing I can pick out.
Now one of the most important things about cpanel (besides its functionality) is its very pleasing and convenient GUI
Speak for yourself. Having used Cpanel a little bit I found it fairly confusing. Granted, I didn't use it long, or more than once or twice, but the thing to remember is that personal preferences play a large part in this. I don't know what kind of usability testing either DH or Cpanel has done, if any, but I personally find the DH panel more usable.
I don’t see how price plays a part in this either, as the “other” hosting companies offer cpanel with there hosting at the same price as DH does, with almost identical specs for hosting packages.
In addition to dollar amount, do also look at flexibility, which Cpanel does not provide. Custom software can be modified in any way to adapt to changes in network architecture or types of services. Proprietary, closed-source software like Cpanel cannot, which means that once you commit to using it, you're forever constrained by what their developers want and how they think you should run things, even down to the operating system you use. Now, obviously the "Cpanel way" works for a lot of hosts, but it won't work for everyone, and especially not for anyone who has their own preferences in how they run things.
So the non-monetary costs can be much higher than just the literal price tag. If it requries making fundamental changes to your network, even free (ie, gratis) software may not be worth the cost.