Hi bcronan,
While other people’s comments about the knowledge and service of a particular business can certainly be very helpful, I would be cautious about using anyone else’s suggestions, experiences or reviews on a specific mattress (either positive or negative) or review sites in general as a reliable source of information or guidance about how you will feel on the same mattress or how suitable or how durable a mattress may be for you. In many if not most cases they can be more misleading than helpful because a mattress that would be a perfect choice for one person or even a larger group of people in terms of comfort, firmness, and PPP may be completely unsuitable for someone else to sleep on (even if they are in a similar weight range).
In other words … reviews or other people’s experiences in general won’t tell you much if anything about the suitability, quality, durability, or “value” of a mattress for any particular person (see post #13 here). Opinion sites like yelp are certainly no exception, and in most cases the “negative” reviews are simply a forum for consumers to “lash out” with ad hominem attacks because they feel they have been “wronged”, when in many cases the issues expressed are a consequence of their own lack of due diligence or refusal to accept responsibility. But since they have a feeling or emotion, they are therefore entitled to make this a reality, regardless of objective facts to back up their point. Certainly, mistakes happen with any company, but I believe most readers are intelligent enough to see through the motives behind many of these posts.
I’m always curious as to why people are drawn toward the negative reviews when reading about companies, regardless of the ratios. Maybe they’re more entertaining. Or since they tend to be out of the norm, perhaps that holds more interest. Regardless, pro or con, reviews like this are the absolute least reliable manner in which to choose a mattress.
Taking your question into account (and I don’t believe that there is a "surprisingly high number of poor ratings), let’s take a look at the yelp site, as I have a few minutes. You have one of the largest online manufacturers producing thousand of mattresses a month, and there are 30 mentions on yelp over a five year period. 25 of the 30 are 5 star – you can give these as much credence as the lower rated reviews. One 2 star review speaks to being “trapped” into picking out a comfort exchange mattress and complained about the company (R & S) asking that they try the product for more time within the 30 day comfort exchange policy (this would have been the store’s policy about which the customer should have been aware). Another “review” claimed is full of hyperbole such as the mattress was a “living nightmare” and claims that “no one” would want to sleep on it. They claim defects, yet this was only seven months after purchasing the mattress, so they certainly would have had a recourse with their warranty if this was indeed the case, but for some reason didn’t avail themselves of this. Another review claims the sales manager at BB (who is an expert on their products) on purpose misrepresented the mattress warranty and also delivered the wrong size claiming it was something it wasn’t, and goes into personal attacks. Another post basically states policies of R & S, which apparently he doesn’t agree with, and then blames them for him not being happy, when he should have been aware of those policies beforehand, and some of what he states has nothing to do with the mattress he purchase. And another review just says they lie to you with no substantiation.
Five years, five negative reviews, 25 positive ones, and they’re all worth exactly what you paid to read them.
Experiencing these types of reviews is part of being in business, especially when you’re one of the largest in any industry. However, my dealings with Brooklyn Bedding and personal experiences with numerous times they have gone above and beyond for their customers would run counter to the negative reviews you referenced. And truly treating customers as stated in these reviews (remember, this is only one side of the story) would go against any company who wished to stay in business, especially one that counts on their high-quality service as they continue to expand.
So with all of that being said, one should focus upon the componentry within any mattress being considered and follow the guidelines expressed in the mattress shopping tutorial. This will provide good objective measures for selecting a mattress.
Thanks for letting me delve into this a bit. I always find these reviews amusing – both pro and con – but especially the con. 
Phoenix