Then instead of trying to figure out whether liking dickgirls is gay or straight, we can just agree that it’s both androphilistic and gynephilistic.

1. By definition, futa encompasses both male and female characteristics. As being gay implies attraction to the same sex, futa can’t be “gay” by definition unless you’re either genderfluid or intersex. If you’re male, it isn’t gay because the female attributes are part of the attraction and if you’re female, the male attributes are part of the attraction. You could make an argument for it being inherently bisexual, but not gay.
    
2. Sexual orientation deals with attraction to a given gender, not sets of attributes. A guy is only gay (or bi) when he’s attracted to other guys, but futa characters often aren’t. A futa character can be (and very often is) identified as a female character who just happens to have a dick. The addition of male genitalia is just an extra piece of biology on a girl rather than being a “male” character. Since the character is usually identified as female, dick or no dick, it isn’t “gay” for a male person to be attracted to them.
    
   Personally, that’s my own experience with it: I don’t consider myself gay or bisexual because I’m simply not attracted to men/male characters. A futa character, despite the dick, is still feminine and female.
    
3. Because I know somebody is going to dredge up the whole “but you like dick!” thing, I think it’s worth pointing out why I think adding a dick to a girl makes them hotter: it’s a matter of identification. In general, I think a picture or story or whatever is more arousing when I can somewhat identify with the characters. I have a dong, thus when presented with a character who also has a dong, I get that sense of identification. Unfortunately, in non-futa stuff that identification is offset by the fact that I don’t find dudes sexy. Futa, however has both girls, and that sense of identification.
    
4. Spinning off of that point, I think a lot of the reason straight guys (I can’t speak for the girls) like futa is because it allows for penetrative sex without the need for a strapon or other toy. Most guys will agree that girl/girl is hot, but for some people it’s hard to get into it because of the lack of penetration, and it’s just not the same when they’re using a dildo or something. In short, futa allows you to have the type of fucking guys do (i.e. one party is actually using their genitals to penetrate the other one) without actually having to look a hairy dude-ass bobbing around, which is one hell of a boner-killer if, like me, you aren’t into that.
    
   TL;DR Liking a chick with a dick =/= liking dudes.
    
   …hot damn this was a long comment. I should just make this into a blog post on fimfiction or something so I can just link to it next time the subject comes up.
    
   Oh, and point 5: so fucking what if it is? Seriously, who cares?