As someone who writes things that involve aliens a lot, I'd just like to say that I see these concerns, and I admit that they're legitimate...but I also think that people probably don't want to see them addressed as much as they think they do.
The fact is that these kinds of things detract from the story A LOT. If you're writing a more emotional story where you only have a few characters developing intimate relationships with alien characters from other worlds, then it's all fine and good; there's plenty of time to get into cultural/biological differences and whatnot.
But if you're writing a story that has just a couple more characters or a little more plot momentum, those little details can get out of control fast. There just isn't always time to talk about those things without taking ridiculously long and pointless detours from the story, so you end up with two options: (1) Just have these really strange aliens speaking strange languages that you never get to explain, or (2) just make things humanoid for simplicity's sake.
I tend to lean towards option 1 with design...and it's a little soul-crushing, to put effort into creating these new races with their unique biology and everything that NO ONE will ever know about unless they ask me personally because in the end, they're just side characters. =/
And with dialogue, option 2, nearly always. Writing in multiple HUMAN languages is difficult enough, let alone writing in languages that don't exist so you'll ALWAYS have to be either translating or justifying whatever you put in...