tl;dr:
Really, I expected you, at least, to be able to see right through a thin and clumsy disguise ineptly draped over an insertion of space lesbians for space lesbians' sake.
A lot of that stuff is just nitpicking. You could make the same sort of criticisms about Fallout, or really any work of speculative fiction. Including hard science fiction likes the works of Michael Crichton.
Crichton is by no means some sort of high water mark for hard sci-fi, especially that he rarely strode out of the five-minutes-into-the-future realm of what is commonly referred to as techno-thrillers.
And sure, a lot of fairly classic sci-fi (mostly TV/cinema) were full of blunders, embarassingly retarded shit or intentional camp.
However ME is in an uncomfortable situation of being somewhat less rubber-foreheady or intentionally campy which makes its blue space lesbian gurls stick out like a sore thumb compared to rather carefully constructed (for an unashamed space opera, at least) rest of the setting, further exacerbated by having its main glaringly retarded feature being clearly designed as fap fetish for horny landwhales.
It's like having stiletto heeled chainmail bikini outfit among otherwise reasonably designed armors and weapons VS having it as part of campy mishmash of bondage gear for suicidal martial exhibitionists. See the difference?
When I facepalm at crew members in ST "devolving" in some primitively looking salamander things the brain pain involved is nevertheless dulled by the fact that I should have expected this kind of retarded blunder from ST occasionally, the fact that it's a flick revolving largely about people with glued on rubber foreheads pretending that they are aliens and that it probably happened purely by accident because the person who wrote that just happened to be a fucking cretin.
OTOH with Asari I know full well that they are part of an assembly of alien races that are rarely humanoid beyond general body plan (more than a handful couldn't be emulated by applying conventional rubber foreheads to conventional human actors, at least) and feature a number of decently thought out concepts (not superb, mind you, but just about good enough to not get a free pass based on rubber forehead logic) and I know full well that they are as much of an outlier only because someone really wanted to have blue space lesbians banging everything, regardless of sex or species, even if it looks like a fucking jellyfish or a goriphant.
It also makes the issue of physical incompatibility crop up in much the same way it does not when the supposed alien races only differ in skin colour and shape of their rubber foreheads.
Their universal attractiveness is spurred by the fact they exude a pheromone (which is the real source of all attraction, not physical qualities) that affects any biological organism. Probably a contribution of the Protheans.
Yeah, well, the pheromones tend to be highly specific, you see.
DraQ
Also you assume that every lifeform in the universe mates based on physical attraction. Even your example, a dog, would counter your argument since they hump everything, everywhere.
Umm... no.
I just assume that there is a good chance many sophonts would mate based on fairly complex set of criteria rather than simple single-stimulus trigger (which is rather reasonable given that complex brain allows you to process complex information and mate selection is kind of a big thing) and that with multiple sophonts having long lists of multiple things they find attractive you would inevitably run into many mutual exclusives between species.
Also consider uncanny valley - almost nailing the right combination with only few extreme outliers may be even worse than completely missing it. There are many reasons to consider uncanny valley not a strictly human phenomenon.
Asari being shapeshifters was something i expected to find out in the course of the game though to be honest. It would fit their concept much more and it would also inherit a nice twist to movies like "the thing" to see such a lifeform behaving as actual social beings.
It would also not suffer from being *inevitably* doomed to not making any fucking sense.
After all it is much easier to be sexually attractive and compatible with multiple alien species when you don't have to be both to all of them at once.
And if you really insist on inserting your fetish into your sci-fi, it really helps to make a plausible cover and a lot of it - no one wants to discover they are actually inside an awful slash-fic when already half way through the experience.
It's fiction's equivalent of waking up in bed with a throbbing headache and no recollection of prior events (barring very sketchy and ambiguous fragments of presumably the earliest and least interesting ones) next to a ball-gagged sheep and a large guy named Bob.