How come girls / women don't seem to be interested

They very much are, they're just likely not sharing that pleasure with a lot of men because they don't want to be roped into the competition that seems to constantly arise when a woman or girl tells a guy she has an interest he believes is inherently masculine. Also, women/girls don't banter the same way guys do - the way guys often talk to each other while group-gaming can be off-putting and uncomfortable for women/girls, and we just want to have fun and unwind from the plethora of things we do in a day when we're off duty and gaming.

Go to any gaming convention, and surely you'll see how many of the paying participants are women, not to mention how much of the merch is targeted at female buyers, from kids to older women. I've gamed my whole life, my former female best friend was a serious gamer, probably still is, and my current close female friends are all gamers bar one, who works too much to game anymore.