MPA,
I don't think anyone is attacking you more so than challenging your opinion. Also, it's not the argument that "undercharging" is good for business, but it's the point that you have to be flexible in order to survive in business. That flexibility could be a reduced rate or enhanced service experience (within MP limits), but there has to be that compromise. Granted, there are many cases of highly specialized services where it is detrimental to business to lower rates as it would devalue the service, but whether that applies to the MP business is a decision between the client and MPA to make. Given the fact that it is a luxury and discretionary expense, I would tend to believe that it wouldn't fall in the aforementioned category, but I could be wrong.
Also, you yourself have stated that you take other factors into consideration and are flexible. This would be in contrast to your stance that rate modifications undermine your business.
Yes there are factors that weigh into what I decide that value is (like demand, competition, season, facilities, etc)
My fundamental point here is that although the MP business is different from other mainstream business ventures, there are still some fundamental principles that apply to all business. In this case, it's the principle of Flexibility. Even in your business, where I believe that factors are tilted favourably to the provider, the provider still needs to be able to adapt on an occassional basis.