not quite in the same area, but this advice reminds me of blizzard and world of warcraft. for years and years, people requested a "classic" WoW (for non-players, the classic version is an almost bug-for-bug copy of the original 2004-2005 version of the game).
for years and years, the reply from blizzard was "you think you want that, but you dont. trust us, you dont want that."
they eventually caved and launched classic WoW to overwhelming success. some time later, in an interview, ion hazzikostas (the game director) and holly longdale (vice president & executive producer), admitted that they got WoW classic very wrong and that the people "really did know what they want".
anyways, point being that sometimes the person putting in the feature request knows exactly what they want and they have a good idea. while your default mode might be (and perhaps should be) to ignore feature requests, it is worth recognizing that you may be doing so at your own loss. after all, you might not not be able to fully understand every underlying problem of every user of your product -- but you might understand how to code the feature that they asked for.