I will concede the point that laptops or notebooks can not be home built, (at least that I am aware of they can't,) but if you're looking for a desktop, building from scratch is the only way to go. For any purpose.
I use to buy into those package deals and I got so frustrated when for one reason or another, I have to be forced to do something a particular way because of their modified "licensed copy" of the O.S. is filled with their name brand quirks. Or their motherboard is wired to run only compatible name brand components, if you need to repair or want to upgrade.
Compaq use to be that way. My last Compaq was the last time I bought a name brand packaged computer. That was a 386. Since that Compaq, I've scratch built all my computers, even for mundane stuff.
I refuse to buy a prepackaged deal. I guess that's why I don't own a laptop or notebook yet. But should the day ever come when I do buy one, I will guarantee you I'll strip the software off that computer to the bare bones and start with a fresh install of a new O.S. so that it will run the way I want it to run, and not the way some name brand flunkie thinks I should run it with all the spamware and flukes of their modified "licensed" O.S.
That's the general idea Snuffy. It's a pre-packaged machine that's ready to use.
For someone who's just getting their first or just a basic machine, a collection of software beyond an operating system is a good thing. they can just boot it up and go.
If someone else is buying the same system and find it comes with some extras that you don't need...they are free to uninstall em.
It's no different than the systems that I built for my customers when I was running my shop a few years back.
Back then, a basic Win98/WinXP computer wasn't really usable...and neither is a new "bare" Win7 rig.
All it has is an operating system. You still need to add the software to do "stuff" with it (MS Office, MSMoney/Quicken, antivirus & firewall, etc...)
Granted, I would custom-tailor the software package to the customer (much like Dell will for ya when you custom order from them) where most of the brand-names send out a generic package.
Nevertheless, if you get more than an operating system then you can just boot up and start doing things besides start shopping for more software that you need to make it capable of anything beyond basic email/browsing.
Brand-name "loaded" computers serve a purpose. If they don't fit your purpose, then you are still free to modify the install to your liking.
Gaming? Again...no. I'll still recommend building over buying too.
Gaming and other specific-use machines (graphics, programming, business, industrial, etc) are still more of a custom deal and a homebuilt rig is still usually the way to go. BUT...the folks needing those machines
know what they need and will build accordingly.