It has a long tradition, as does decorating arms.
Again, I don't necessarily grok the idea behind the decoration or personalization of what are, to me, tools, but that's just me. For all I know, some people dig racing stripes on their Sawzall and have named it "Suzie".
Some guns provide better platforms on which to write stuff than do others. The AR, with its big, flat expanse of magwell, has spawned a whole cottage industry of laser-etching.
You can also get replacement ejection port cover doors with stuff etched onto them, from your branch of service to "Semper Fi" to cute stuff like "Zombie Hunter". I had a fleeting thought that the M.H.I. logo would look kinda cool there, but I got over it; like I said, I'm just not much on decoration. If there was such a thing as a Shaker-styled gun, I'd be on it like white on rice.
I don't know that I'd term it "tacticool", though. I mean, people have been decorating weapons since long before there were malls, or even ninjas to put in them:
"Ha, Beowulf, I notice that your sword says 'Hrunting' in the serpent patterns on the blade. You are such a Mall Berserkr!"It just doesn't scan for some reason...