Society’s attitudes towards written communication are changing. This is not simply a matter of the eternal development of language, though that, of course, goes on, and at an accelerated pace in any time of great social or economic change. There is also a difference in the relationship between the writer and the reader.
We might easily dismiss this as simply becoming “less formal” — a development you will either welcome or disdain according to your taste. And we might also too easily see as growing informality what is really just the diurnal migration of vocabulary. I would suggest that what is happening is something more precise and more important than that: the relationship between writer and reader is becoming more collegial.