I think your suggestions won't succeed. If the device isn't intuitive to the user, they'll give up. If you look closer, you may find that the highest returns are among the devices that don't have easy to use interfaces. Don't rely on instructions, the users won't remember them, especially if they have to remember vastly different instructions for different devices. If needed, make a user's manual that's actually useful; most I've seen make good use of my engineering degree, not my wife's mass communications degree.
I work in healthcare, and we see a LOT of users that struggle with the equipment. Thankfully they get to try it out in the hospital before purchase (clinical trials); if they don't find it intuitive to use, it lowers the chance of purchase.
Excuse me. You said, "Online certification programs, perhaps including special rewards to candidates who complete their certification, are a good way to ensure successful education of retail professionals."
"Retail professionals?!?!" Go to a consumer electronics retail store - Radio Shack, Circuit City, Best Buy, Target, Walmart. Most of the people selling this stuff ARE STILL IN HIGH SCHOOL (hopefully they haven't dropped out yet). You can't get them to do their homework, but you expect them to get some education in excess of school?!?
Try making easy-to-use products. Keep the complexity down. Keep consumer devices to a single-purpose (or maybe a very few limited, related purposes). My cell phone (Nokia 1112) lets me talk to people, send short text msgs to other cell phones, and keep a list of phone numbers. I don't need it to play music - I have a Sansa player for that. I don't need it to take pictures - I have a Fuji S5100 for that. I don't need it to surf the web - I can do that at home or on my laptop. I don't need it to play games - I have a mit, stick and ball for that.
It's the interface. Not training. Although training is a great thing to do to to help improve productivity and enjoyment of users, a consumer product has to be simple enough that you can do what you want by just inserting a battery or plugging it in.
I think the authors have taken a rather self-serving view of this problem. Although not even mentioned in this article (but in lots of other places), the MANUFACTURER is often to blame for overloading his product with "features" and overly-complicated layers of menus. In my own experience, I've accidentally set something in an obscure buried menu that results in "I wanna throw it against the wall" frustration. And dealing with customer support is often even more frustrating as the "technicians" are obviously just following a script on their end of the phone. I'm a big believer that DaVinci was right: "Simplicity is the ultimate sophistication". Manufacturers shouldn't load up on "features" just because they can!
I agree with the comments above and was shocked to read an article about returns that doesn't even mention the most obvious reason: User Interface. Engineers often have a hard time thinking like non-technical people and design products that only engineers can appreciate. I'm a Ph.D. and it is still confusing hooking up some gear these days. To the extent I hit obstacles, other non-technical people give up and return or don't get the benefit of their purchases. TiVo is the probably the best product interface design in the last 20 years and standardization of interfaces/cabling (e.g. HDMI) will help. In any case, this reason is a critical factor in returns and should have been discussed in the article.
Getting quality answers from the 'retail professional' is usualy a joke. Last week he was flipping burgers, but today is experienced and knowledgeable about dozens of complex products? - I don't think so. The manufacturer has to really step up and give clear, complete, accessible pre-sale information.
I think the manufacturers play an odds game here and are just paying for sometimes being on the loosing end of the deal. Funny commercials, pretty boxes, incomplete information - whatever they can do to get you to buy the thing - in hopes that once you get it home you will just live with the shortcommings (that the clear [for non-tech people], complete, accessible pre-sale information would have revealed) and not go through the bother of returning it.