I'm gay and I'm hopelessly, passionately hoping that Vivienne is available to male inquisitors.
Not really if they have 4 Hetero, 2 Gay/Lesbian, 2 Bi/Pan. That is a "satisfying some arbitrary number" if there was something like 3/1/4 that would be not. The same way that there is only three female companions and six males. So it appear they do the "satisfying" when comes to sexuality and romance per gender.
It's only satisfying some arbitrary number if they set out from the beginning to do so. If they mandated at least 2 options for your sex/sexuality choice and decided to make 2 more from the remaining characters, this second step isn't going to result in satisfying an arbitrary number, even if the first step was. That is to say, If, from the remaining characters the most likely to pursue a romance are unlikely to be bisexual (or more accurately, willing to pursue a relationship with either sex*), they shouldn't change their character to fit a number scheme. IMHO that reduces the entire worth of a character to who they'd be willing to bed, which I believe to be shallow and ridiculous
To expound, if their characterisation process for Solas went "He must be open to both sexes to be fair therefore we have to remove or downplay (or even just despite) the bit about him being impassioned to the cause of Elven survival (since it would be hypocritical for you to pursue a relationship with a male elf, while at the same time turning down a human/dwarf/qunari if you're so gung ho about making elven babies)", I would be pissed.
*There's nothing stopping a person from being bisexual and only pursuing a relationship with a female in the interests of reproduction. Solas could still have been bisexual and force himself only to accept the advances of a female. Furthermore, I can see Vivienne being attracted to all races, but choosing only to pursue a relationship with a human because it would sabotage her life's work etc.