I don't think you've done anything to substantiate the claim that it's "too complex"; forgive my skepticism but I've spent enough time in both the Scala and C++ communities to draw a significant line between "too complex" and "critic hasn't learned it sufficiently" (and I've been on both sides of that line).
I have spent a nontrivial amount of time with Kotlin and Ceylon and neither are particularly interesting to me after actually internalizing and understanding Scala; as an example, I am significantly hampered by their continued insistence on mutable-everywhere (which is basically the watchword for "barely adequate programmer"). They may very well be "the next Java", but that's a curse more than a compliment. You should not need Guava to write minimally competent code.
Meanwhile, as a sibling comment notes, Twitter's a lot bigger than Yammer and pretty vocal about going whole-hog on Scala (and I've talked to them a little about what they've done, it's insanely impressive, I'm jealous). Guess they're just making things hard on themselves for no reason though.
Linus Torvalds is in the C++ is too complex camp too AFAIK :)
I believe that Ceylon is the best-designed general purpose language out there. What do you mean by "mutable-everywhere"? Ceylon's variables / attributes are immutable by default.
I have spent a nontrivial amount of time with Kotlin and Ceylon and neither are particularly interesting to me after actually internalizing and understanding Scala; as an example, I am significantly hampered by their continued insistence on mutable-everywhere (which is basically the watchword for "barely adequate programmer"). They may very well be "the next Java", but that's a curse more than a compliment. You should not need Guava to write minimally competent code.
Meanwhile, as a sibling comment notes, Twitter's a lot bigger than Yammer and pretty vocal about going whole-hog on Scala (and I've talked to them a little about what they've done, it's insanely impressive, I'm jealous). Guess they're just making things hard on themselves for no reason though.