Interesting that "mental laziness" is the association you have with this construction. It certainly signals a sort of casual tone, but it's easy to fall into the trap of "different than the way I speak" -> "wrong". Certainly not helped by the fact that young people are the ones who generate and adopt language changes at a vastly higher rate.

"Laziness" in language change generally follows the principle of least effort - both in syntax changes as well as phonetic and phonological changes. We're almost certainly beginning to see more sweeping effects of shortened communication media on English, beyond the near-ubiquitous acronyms now in use.

I have nothing against brevity. And I don't think it's lazy because I don't speak that way.

To clarify my thoughts, I think it's one thing to use a prepositional because when referring to oneself. However, it's another thing to criticize someone else with a five syllable simplification. It's impossible to do justice to someone else's thoughts and feelings that way. That lack of understanding and empathy is what I find to be lazy.

Now, a full-length column in the New York Times or a bit on Fox News certainly is not necessarily a fair and coherent argument. But, leaving room for exceptions, pithy "because X" clauses are not fair to third-party subjects.

I think we are in agreement then. I certainly wouldn't use a construction like this in a serious critique. But then there are thousands of other things I wouldn't write or say in a serious context either.

> Some of this might be caused by increased use of smartphones

I actually find it more effort to type full English sentences with a keyboard and mouse; my Android smartphone has voice dictation and swipe gesture typing, and I find that iOS' autocorrect appears to trigger most when you type something that isn't a "standard" sentence.