Dell is my preferred laptop brand, but these shared keys on the arrow keys are unusable. I don't use desktops, so my laptop is my main workstation and I use these keys very often.
Ever since Dell got rid of the last row of buttons, I had to look for other options. They claim that it makes the laptop more compact, but there are still ample space on the sides. Look at the Dell Precision 5520 as an example - wide open spaces. I liked their older design much better with the shortened right shift button and full-size arrow keys and home, end, pg up/down in the last row.
I now have a HP EliteBook 1040 G3 instead. It's only 14", but comes with a much better keyboard layout. That was actually the deciding factor. It would have been a Dell otherwise.
I know many other people are also feeling the same way, so I hope R&D will address this. I'll gladly switch back to Dell once they do.
Yeah, this has come up quite a bit, especially on the Precision models where as you say there's space. I have a Precision 5520 and a Latitude 7480. Not only does the 7480's keyboard feel better, but it has dedicated PgUp and PgDn keys right in a space where the 5520 has....nothing. Would have been easy to at least add those. As for Home and End being shared, my previous system (a Precision M6300) had all of these navigation keys in their proper 3 across, 2 down arrangement in the upper-right corner, which I loved, so using Home/End as shared keys was annoying at first -- but I have to say, after really setting my mind to it, I got comfortable with it after about 2 weeks, and now I don't have any real problem switching between my 7480's keyboard and my Das Keyboard Ultimate, which has a traditional layout.
Anyhow, these complaints came up frequently on NotebookReview in a thread where a Dell Precision product manager is active, so I think there's a chance things will improve with the next refresh.