Here's the thing: making coffee, especially with manual methods (and seven of the nine methods are manual) takes practice. And no one recipe will suit everyone. Some people (and I'm one) prefer their coffee on the weaker side. Others like it strong. Some like their coffee full of dissolved particles, and others like a perfectly filtered cup (a "clean" up in coffee lingo). Some people like light-roasted beans, and others like their beans dark. Some like their coffees brewed with finely-ground beans, others medium, and still others like their coffee made with coarse grounds. Flavors, and strength are all dependent on a bunch of variables. Temperature of the brew water, the freshness of the beans, the grind size, the timing on the brew, etc.
The reviewers simply followed the manufacturers instructions. With any coffee-brewer, the instructions are meant to be a starting point. If your coffee is weak, then you have many options: add more grounds, use a finer grind, or brew for a longer period of time. You can try hotter water (though the closer you get to boiling, the more bitter it will be).
Here's what they said about the Sowden Softbrew:
As much as we loved this coffeemaker, it just didn’t win the people over. When following the manufacturer’s instructions we got a weak pot every time. While we appreciate the sleek design and the fact that some tinkering could produce us a better cup, it didn’t stand up next to the other brewers. Here’s what our tasters thought: “Strong aroma, weak flavor.” “No flavor.”At least they did some tinkering. But... the fact that they thought it was weak or lacking flavor means they didn't tinker enough. One of the characteristics of immersion brews like the Sowden (and the Duo, and French Presses), is that they are less filtered. They allow the coffee oils into the cup and tiny particles (sometimes too many of the latter, forming sludge in the bottom of the cup), which means they have more flavor (or perhaps different flavors) and mouthfeel than many other kinds. And, like any brewing method, they can be adjusted to be stronger or weaker, depending on preference.
Disliking the Sowden because the included recipe produced weak coffee, is like disliking a stove because you didn't like the pancake recipe you just tried.
I admit it, the Sowden is one of my favorite brewers, and the fact that they didn't like it was annoying, and I know I shouldn't care. But, they complained about a percolator, too. I don't particularly like percolated coffee, but I bet that if I found someone who liked their coffee similar in strength to my own preferences, and who knew what they were doing, they would probably produce a good cup with a percolator.
I like the Chemex (their top-rated brewing method), but even that takes practice to get right.
Sigh... I can't help but wonder how the results would have turned out, if they'd done a blind cupping, and the coffees were produced by people who specialized in that particular brewing method?
I was also suspicious of the placement of the two automatic coffee makers. Is it any wonder the fancy (and very expensive) coffee maker placed second, and the Mr. Coffee far down the list? Maybe the fancy one really IS better. But did the reviewers know the price of the two automatic coffee makers before they tasted the samples? Were they expecting better brew from the expensive one, because it must make better coffee, because it's 10x the price of the cheap one?
Yeah, I suspect confirmation bias.
Either way, when you try a new method of brewing, expect to play with it awhile, before you get it right. Vary the water temperature, the brew time, the amount of grounds, how fine or coarse you grind them. If you do that, you'll get a good cup out of just about any brewing method.