There is a simple reason, and it is certainly not stupid. It is all about credibility.
USPAP says that credibility is achieved via support by evidence and logic. Well, the 1004MC form should contain the evidence and logic that supports the trends that have been indicated in the neighborhood section.
The reason we now have the 1004MC is the fact that so many appraisers were just checking boxes without looking at any data or doing any analysis. As a result, they missed big market changes, or were very late to see (and report) them.
I'll agree with the last part about prior report analysis.. But regarding credibility, the mc form and neighborhood section ask for two different sets of information ( and to be credible appraisers should clarify about each )
The first page addresses neighborhood and trends of subject neighborhood, do you agree neighborhood addresses the relevant location boundaries where subject is located and those boundaries may include properties not similar to subject? The neighborhood trend asks about activity of sales and inventory in subject neighborhood, which includes sales and listings of properties not comparable to subject but located in location neighborhood boundaries.
The MC form asks about only sales of listings of properties similar to subject that could be considered as comps for subject for use in report. These comps may be in neighborhood or located out side of it. There are typically fewer comps for subject, and the trend of sales /listings similar to subject may differ from trend of neighborhood property sales/listings unlike the subject.
The appraiser has to be credible for both sets of information and explain that they can differ, because it can tie in with other elements of the report. If subject is a luxury home of 6000 sf in an neighborhood boundary that includes mostly smaller less costly homes of 2000 sf, after gathering 6000 sf range home comps from beyond neighborhood, appraiser may conclude subject size makes it an over improvement, for example. If appraiser gave results of trends from MC form of 6000 sf comps selling for 800k and put them in neighborhood trend where the predominant homes are selling for avg of 450k, it would be misleading and make subject look like it conforms to neighborhood while in fact it does not. The prices of smaller surrounding neighborhood homes may be rising, while prices for large luxury homes are stable (or vice versa) .
We can't over correct for problems of the past by asking for a degree of conformity now that makes reports actually less credible, while giving the appearance of being so by making everything match up neatly on report.
There were appraisers in the past who did analyze and report neighborhood trends as they actually were...only many mtge brokers or loan officers threw their appraisals in the garbage and ordered an appraisal that reported neighborhood trends that looked good on paper and made the deal work. One cause of problems seen in appraisals arise from what lenders accept and who they choose to use.