there's your first problem.
building it yourself is the only way to go...twice the value, one afternoon's work.
Maybe this was true 5 years ago. It certainly isn't true now, unless you actually want a specific case.
PCs are too cheap now for building from scratch to be worth it. Most of the objections you mentioned (such as partitions and bothersome software) are solved by a complete wipe/reinstall from the start. As far as not being gaming-ready... anyone who really wanted a gamping-specced computer probably wouldn't be buying a Dell off the shelf anyway.
I won't build computers for family/friends any more. It's just not worth it.