Ampersand slash ("& /")

I admit, I'm guilty of this, but when did "slash" become a substitute for ampersand (or "and" when spelt out)? Or for "or" or for "I can't decide which of these two words I want to use so I'll put them both and put a slash between them"? (And how'd you like the start of that last sentence? "or" and "for" for the first five words; three letters used twelve times in five words!) This is becoming more and more common/frequent (see?). Are we, as a literary nation, becoming:

1. more efficient - using fewer characters in expressing "and" or "or" (then again, wouldn't it be more efficient to just pick one of the words and omit the other word and the ampersand/and/or/slash altogether? especially in a tweet, where you're limited to 140 characters, saving the two spaces around the "&" seems to pale in comparison to saving the spaces, the slash, and the characters of the second word)
2. lazier - putting the slash instead of the whole and/or/ampersand thing (then again, laziness would tend toward omitting one of the word choices, too, wouldn't it?)
3. less decisive - perhaps the "/" is seen more as a "I can't really decide which word I want to use, so I'll give you options, pick the one you like the best (then again, why do you need the slash in this case? wouldn't the "and" or the "or" or the "&" be just as good?)
4. too "techy" - I mean, hey, there are "//" in web addresses and stuff, so why don't we start putting some "/" in our text, too?

This is, I think, just another step in the degradation of the English language (see my other related posts). Then again, is written communication itself becoming a thing of the past? Think about it (warning: another numbered list is coming!):

1. text to speech and speech to text are quickly becoming commonplace; modern cell phones have the processing power to handle both tasks in a fairly quick manner, and are fairly accurate about it, too.
2. neuroscience is advancing (how quickly? I don't really know, but this site has some interesting information about it); how long will it be before brain-computer interfaces (BCIs) replace input/output devices (note: input/output, or I/O, is an accepted term, and has been around a while), such as keyboards and screens? Instead of pulling your phone out of your pocket, you'll be thinking about who you want to call, then you're "thinking" with them if/when - sorry, if and when - he/she answers. (OK, not sure about the he/she; should it be "s/he"? should it be "he or she"? should I just use the masculine "he" as a reference to a singular entity regardless of gender?)

Science and grammar - hand in hand, or is the one defeating the other?