There are three perspectives: the company's, the freelance writer's, and the customer's.
-Company. You presented a good case for why companies need more money. I'm not so sure that customers see that as a reason that they should pay more. I also don't see it as a reason for freelance writer's to charge less. (It might be a reason that they could charge less, but not a reason they -should- charge less.) I was curious as to what additional value a company brings that would make it worthwhile, in a customer's eyes, to pay for the company's overhead.
-Freelance writer. There are probably very few writers who make their entire living from private clients. Most also work for the companies. The work is all pretty much the same, and I'd think the quality is the same, on average. As a writer, unless you think you can't do a very good job, I see no reason to charge less than the companies charge. I see no reason to undercut the companies, because I don't see any evidence that, in a head-to-head competition, customers have any particular preference for companies.
-Customers. I don't know what they "prefer" or if they have a strong preference. Mainly, they just want a good paper at a reasonable price. The companies are easier to find. They're likely always to have a writer available in the subject you need. I think customers like having a personal relationship with a writer, but they don't know where to find someone they can trust. If things go wrong, they might feel they have more recourse with an established company. Are they willing to pay more for those benefits? Who knows?
In summary: I don't think most customers have a strong preference either way. Therefore, I don't see any reason that freelance writers should charge less than companies. The overhead costs are the concern of the company, not of customers or independent writers.