I have used +"a phrase" and gotten a different result from just "a phrase" combined with other words on a number of occasions. It was part of my search strategy for complex information.

This just dumbmifies Google search a little more...

It's like a bad dream, I used it daily to filter results. Why would they obsolete that?

Because they want to give competitors an opening~

It may be related to the +1 stuff, or they may need to clear the way so it can be used for a new purpose.

I've assumed quotes meant one or more words were wanted in that order, not as keywords ("to be or not to be" = I don't mean a lot of documents including all those words, but rather that exact phrase) whereas + meant that particular word or phrase had to be in the page (melting abs +plastic = I'm not concerned with placement, but the term "plastic" has to be explicitly mentioned on the page, not related from another page, as I'm wanting to melt ABS plastic as opposed to reshape my abdominals). I considered + as the opposite of -, which is usually the easier way to narrow something down (melting abs -muscle -workout). Oh well..

And I believe that this was how it used to operator.

Always used it for phrases of two or more words and around a year ago started using it for specifically worded single words since Google likes to autocorrect me. I always assumed it did what the + did, but never had definitive proof.

Nope. I always assumed exact matching was simply broken.

Nope. I haven't used + since Lycos and co. Now - is a different story altogether.