At an adult level, people are getting lazy.
In spoken communication, it cuts in too much of the time to correct each error (destroys continuity). There's a better case for it in written text, but since people often don't like being told they are wrong and/or they think it's "petty" in light of the greater topic, you end up with the "attack" (which ironically requires more effort than just copping the correction, i.e. who really started the fire?)
If "aswell" becomes a new word, I might just eat a hat. I have to admit, I don't come across that often as much as it may just be a general forgetting to add a space (or when tapping it out on a mobile screen, it can happen when the spacebar is missed or when inserting autocorrected words).
I'm currently teaching at a high school. The spelling, grammar and punctuation of some of my students (who should know better, not that they are EAL/D students) is pretty shocking. This extends to when they have to write code as well, since some of them said that their code which they copied from my example didn't work, and then I realise it may be because they spelt "height" incorrectly...