It won't be about "appealing" to anyone, other than a small demographic. Unless your aim is to sell to gay folks of one stripe or another, and I can't think of too many products in that category. What products are relevant strictly to gay folks? A particular holiday destination, perhaps.What was the SSM survey result in the end? 62% yes, 38% no - thanks Wikipedia.
That's why same sex couples don't feature prominently in Australian commercials, it's a commercial decision. Advertising appeals to the lowest common denominator.
If you don't feature a same sex couple in a commercial, then you don't upset the 62% or the 38%. At worst you might upset that 1% who are outraged by anything that doesn't include every race, gender, religion etc. under the sun.
If you do feature a same sex couple in a commercial, you potentially appeal more to the 62% but risk upsetting the 38%.
(Side note, $40m of the $120m budget for the survey wasn't used. Where did it go?)
With regard to that kind of advertising, it'll come when those who'll sit through it without flinching are an overwhelming majority, even if for no better reason than to prove how progressive they are - when they're in company. I'd imagine most will go and make a coffee, if they were alone.
If you were to reverse the question, for example, how do gay folks react to commercials specifically aimed at straight couples? Are they likely to rush out and buy whatever is being sold?
Advertising isn't designed to appeal to the lowest common denominator. It has a target market, which may or may not include that demographic.
I've got no idea how many people are gay. Or whatever letters of the alphabet the non-straight self-identify with now.
Unless you have a product which is aimed specifically entirely at the gay market, there'd be little point.
Or it might conceivably be aimed at the virtue-signalling SJW market who'll go out and specifically shop at your store because you advertised using gay folks. I wonder if they're a large enough demographic yet? Probably not. Getting there, though.
Still, though, reading through this thread... it's interesting that there are so many who think television is, or should be, a social engineering tool. It's a business.