Imagine how much money you could save by having a keyword related domain? Yes brandable names are fine providing you are well known, but what if you are starting out and want the world to know who you are?
This is where SEO link wheels come in. So you have launched your brandable website which is not known to the world and probably people will not even search for your name so what do you do?
You then hire a marketing company to advertise your name. Imagine if there was a simplier way to get on the first page of google with a keyword related domain.
What you do is you launch your site which is the mothership but you also launch another forwarded to you main site with your keyword related domain. The name will change in your address bar on your browser automatically showing you your branded site.
I have attached a link to 25 most expensive keywords of all time. If you had a budget of £3.00 per day you would not even hit those keywords meaning you would less likely be found. Hence owning a keyword related domain makes more sense.