Connecticut's system would seem to be more logical since the property interest being released belongs to the grantor. Connecticut is a title theory state rather than a lien theory state. When the title holder records a mortgage in Connecticut, he does more that place a lien on his property. He actually splits the title. He conveys the legal title to the mortgagee, and retains the equitable title (the equity of redemption) for himself. However, Rhode Island may have some logical reason for indexing it in the alternative. 

If you have ever searched in New London, Ct you are familiar with the peculiarities of their indexing that do not seem to be used in other areas of Connecticut. For a time any grantor or grantee whose business name began with the word "The" was indexed under the letter "T" regardless of the business name. Although I have not run into it yet, I have been told that there was an approximate six month period in which the entries to the grantor and grantee index were reversed. In some years of the tax lien records the names of the title holders are not alphabetized requiring the search of the whole tax roll of liens (could be several hundred pages) recorded  for that year to make certain you have everything. In some years the tax liens are indexed in the grantor index under the volume and page of the first page of the list of liens for all title holders, but the release references the volume and page on which the the individual title holder's lien appears. 

Whether the method of indexing is "right or wrong" is a subjective decision
determined by the individual, and made in accord with the standards with which he is familiar. As you know Connecticut's land record indexing is a patchwork of inconsistent indexing methods left to the discretion of each Town Clerk. No matter how much you may complain, they are not likely to make any changes. Rather than trying to determine which is right or wrong, it is more productive simply to learn the peculiarities of each Town Hall, and keep them in mind while performing the search.