Google (and all other search engines) try their best to return the results the user has asked for.
More precisely, they try their best to return the results they infer that the user would really want, based on the syntax of the query.
It's never going to be perfect at doing this, if only because people use the same phrases in different ways from time to time.
Yes, it's never going to be perfect at inferring what the user wants. The original poster is complaining that Google has been getting worse at inferring what he wants, especially for particular narrow queries.
I've seen the same problems he has. Perhaps that's an unfortunate side-effect of trying to do a better job of handling most users' queries.
If Google (or the search engine of your choice) is returning results that aren't what you want, then your best option is to make the query more specific. Either add relevant keywords, search for a phrase instead of individual words (using quotes), or exclude some other keywords (in Google, prepend - to the beginning of the word you want to exclude...other search engines are probably similar).
Yes, the original poster is quite aware of quoting; as he says, "Searching for exact strings is an option with Google". What he wants is a search engine that doesn't try as hard to infer what the user really wants, rather than one that has to be forced, with more use of quotes, to just look for the damn string. Perhaps that's a sufficiently small niche that no search engine would bother to offer that, and he'll just have to live with typing more double-quote characters.