For books meant for scholars concerned with textual criticism, yes. For books meant for the general reader, no. For the general reader, such footnotes are just a distraction.
Comprehensive footnotes or addenda are meant for scholarly editions where a main purpose is to point out the differences between various versions of a text. For Bhagavad-gita As It Is that might be useful for critics and scholars, but for the general public—worse than useless.
Speaking about this type of scholarly apparatus, one scholar says, “The more detailed and complete an edition is, the more cumbersome it becomes for lay readers, and by lay readers I mean those who are trained to read scholarly texts if need be but who also simply wish to have a readable yet reliable edition.” (Richard Exner, from “Editing Hofmannsthal,” in Editing Twentieth Century Texts, p. 54)
Hridayananda Maharaja, sometimes cited as an advocate of adding footnotes, wrote in February of 2003, “I agree that the general public doesn't need a lot of notes. If both editions are available or if there is a ‘scholarly’ edition available, apart from public distribution, then reasonable people should be satisfied.”
Going beyond a mere scholarly edition, the BBT has begun a project to extensively document the editorial history of each of Śrīla Prabhupāda’s books, tracking the details of the text from manuscript to the most recent printing.