I don't know that I'd call them a gimmick, but I would call them an answer to an unasked question. The things they supposedly help with are only matters of very small importance; the recoil spring in a 1911 generally doesn't bind anyway, and the weight at the muzzle is generally pretty small. However, they do indeed complicate disassembly (but IMO, not by much), and the two piece ones can come unscrewed (mine never has, but it can happen).
Generally, if a 1911 has one, I don't run out to replace it unless it becomes an issue. If a 1911 doesn't have one, I'd never add one.