Actually, changing issue type is a VERY useful feature. There are many issues where a rule catches a lot of things that aren’t that bad. (See S2111 should check for integer equivalence for example.) We could mark them false positive, but we’d still like to direct attention to them, just not as urgently as the true bugs. So “demoting” them to code smells is one way to do that.
The security hotspot type was created, if I read your documentation correctly, to identify POTENTIAL vulnerabilities that could also be benign, but where automatic analysis is impossible. SQ metaphorically shrugs and says, “I don’t know, but you’d better take a look at this…” So again we may want to mark the benign cases as smells if we feel that the code could be done better (otherwise we’d mark it falsepositive).