Yeah, random bikini babes don't really make a lot of sense when there are plenty of good looking women in the shooting sports that they could use for both eye candy and relevant celebrity endorsement.
No one seems to care whether men in magazine gun ads are real seel teem operators, or IDPA/3-Gun/SASS champions, or hunters (except for that guy in that gun control ad a while back). I don't care if the girl/guy in the ad knows an Enfield from a Springfield. I just think the gun-bimbo thing is a totally avoidable way to play into the under-endowed male gun-owner stereotype that doesn't much help the movement. Of course, for some gun magazines/websites, it fits their ethos. Like American Handgunner. Or The Truth About Guns, before they decided to quit talking incessantly about Israeli models.
And some of the ads are just very poorly done, like the gun-leg thing above. On the other hand, there are some much more classy ads, to which I suppose no one will object, but the snowflake crowd. Or people that don't like weird, curved, plastic guns.