There’s a huge rabbithole to go into about visual language and aesthetic coding.
Star Wars original trilogy was Flash Gordon meets WW2, but with an added layer of grime and strange extra details to keep it from exactly being either of its main influences. Not just with the blasters, but with everything.
Star Trek started out with Flash Gordon raygun looking phasers, because probably in the 1960s they just thought it was the thing to do. In TNG the dust buster phasers were an intentional choice to signal a kinder, gentler Federation. It’s easier to look non-threatening without a big iron on your hip.
Stargate guns needed to be recognizable as modern military, but all the normal choices would be generic. An unusual gun gives the show more of an identity. In the first couple of seasons they used MP5s that had Colt scopes on them to make them more unusual than a normal MP5, but eventually they discovered something more unique with the P90. Given that decades later the sight of a P90 makes people talk about Stargate, I’d say it worked.