Google has provided an explanation for dropping the ~ search option. Dan Russell is quoted as saying:
"Yes, it's been deprecated. Why? Because too few people were using it to make it worth the time, money, and energy to maintain. In truth, although I sometimes disagree with the operator changes, I happen to agree with this one. Maintaining ALL of the synonyms takes real time and costs us real money. Supporting this operator also increases the complexity of the code base. By dropping support for it we can free up a bunch of resources that can be used for other, more globally powerful changes."
So let's break this down a bit. If too few people were using it, why didn't Google promote it rather more? That's a very weak argument. Google is happy to promote other things that they do, but oddly enough, when it comes to search functionality they're very, very quiet. It would be easy for them to suggest its use - when they do the basic synonym search or a 'did you mean' they could very easily have slipped in a suggestion to use it.
It takes time, energy and money to maintain it. Google earned $50 billion in 2012. They really can't use the argument 'we can't afford it', particularly when search is key to much of what they do. On the other hand of course, if they make it harder to find stuff when you search, and there's a useful little advert on the side, which will make them money, it's going to be hard to improve search in organic rankings, and therefore lose the opportunity to add to that $50 billion. Or am I merely being overly cynical here?
Maintaining a search function costs them money. Here's the nub of it, and it shows just how money grabbing Google is. I get that they're there to make money, I have no issue with that. However, there comes a point when, if they continue to degrade search functionality people WILL go elsewhere. But I think they are hoping that people are just far too lazy to do that, and they'll accept whatever junk Google throws at them. The point is - when the bottom line is money over the ease of use of the search engine, or the better results for the searcher, they're going to go for money every single time.
Increasing the complexity of the code base. How many coders does Google have? And isn't it fair to expect that they'll have some of the very best in the world? Ah, but that comes at a price doesn't it, and Google's already pointed out how important that is to them.
As for the other global changes, I'd be interested to see how Google is using their coders on other stuff, and while they're at it, I'd be fascinated to know just how much they're saving by removing this search function.
In short, as I have said before, and will say again, Google is not a search engine company, it's an advertising company. While I'm at it, a librarian is there to help you, Google is there to make money.