Keyword Searching is different than subject searching:
"Keyword Searching searches in any number of fields; any significant words can be considered keywords; number of items retrieved is potentially large; Keyword Searching may retrieve irrelevant items
Subject Searching searches only in the subject field; search terms must come from the database's thesaurus; number of items retrieved is potentially smaller; there's a high degree of relevancy".
My main interest is to get high degree of relevancy from search engines. According to the above comparison if we could have replaced Keyword Searching with Subject searching we could have solved this problem, but Subject searching needs manual processing and the amount of documents that need that kind of treatment is enormous and growing from day to day. In fact that's why Keyword Searching became more prevalent than Subject Searching in Keyword Searching we can use millions of documents that weren't processed.
So we had a system of high quality search and moved on to another system with low quality search and now we are stuck with the fruits of our choice.
In Hebrew Keyword Searching relevancy is even worse since "Almost every word in Hebrew script can be read as one of an average of three words".
I believe that Automatic Tagging is the way towards a solution of this problem. Automatic Tagging will process millions of documents and enable their retrieval by tags which are in fact Subject Searching tools.