I think, personally speaking, what feels most important in queer representation, especially in the case of large milestones like this is the notable involvement of queer individuals, from writing to direction to portrayal. I don't think its inherently problematic for straight actors to portray gay characters, and in fact I've seen some really excellent portrayals that have connected a lot with me personally which came from performances by straight actors.
I think the notion that causes, at least in my perspective, the real discomfort, are examples where, in these relatively early days of LGBTQ media representation we're seeing major examples of representation which appear to be helmed (both behind the camera and in front of it) by those who don't have first hand understanding of what it is to be queer. I'm excited and happy for more representation but it leaves a bit of a bittersweet taste in my mouth to consider the notion that the first major mainstream examples of gay characters are being done in large part by straight writers, directors, and actors on behalf of the LGBTQ community, building those forms of representation from second hand sources, observations, and other forms of media.
Growing up in a world that appears, at best, uncomfortable and unfamiliar with who you are makes the media that tells you that somebody understands you and somebody is like you so incredibly important. Were we to look behind the curtain and realize that these stories were in fact not made by somebody like us or somebody who innately understands what we're going through then it becomes a tragic loss of much of the peace and progress that comes with having and seeing that kind of media in our landscape.