Even Dell's VALUE Pc's are great, for a SPECIFIC MARKET.
Basically, you get what you pay for.
You don't go out and buy a Ford Focus, hoping to trick it out and make it a street racer, do you? No. Sure, it may have some of the same features as other cars you want (same top speed, same gas mileage, etc), but it's not suitable for upgrading.
It's the same with computers.
We use Dell almost exclusively in house, and after years of dealing with our old IT Manager's "bargain, value" PC's or self built PC's, I'm thrilled to have Dell's machines in here. Sure, they're not all that upgradeable, but for a business market, that's not a huge deal. The machines get as much use as possible. When someone outgrows it, it gets passed down the line to more mundane tasks, until we finally get rid of it and replace it.
For a home PC, if you're a casual internet user or Office user, and don't use your PC for gaming or heavy video/image editing, a Dimension 3000 is an excellent choice for you. You probably won't upgrade it for a few years beacuse you won't need to, at which point you've gotten the $400 you spent on it out of it, and can go buy a new dirt cheap Dell PC.
Even if you go and buy the top of the line brand spanking new $2,000 PC, you may actually have reached THE TOP OF THE LINE, as far as your hardware is concerned. If the next newest chip after yours uses a different socket, or an unsupported faster clock speed then YOU'RE SCREWED FOR UPGRADING ANYWAYS (unless you replace the motherboard).
Basically, it comes down to buying the right tool for the job. You wouldn't go and buy a tiny little garden spade to shovel your 1/8 mile long driveway, You'd go out and get a snowblower. So don't go out and buy the smallest, cheapest, crappiest PC your OEM offers, then get pissed when you can't upgrade it.
As for the Capacitor issue, that's a nichicon issue, not a Dell issue. Dell got screwed on that deal, because they had no idea those caps would be defective. I've seen issues with Nichicon caps in house also.