Well, besides that you gave the right answer, Turner, i find it disturbing too. It would be more intuitive to only use whitespace as delimiter.
But, there is a reason why it's currently so in DokuWiki. Because one of the concepts behind a Wiki is, that if someone searches a word and do not find it, he should be able to create a page for it immediatley. This is the point why you're directed from current- to root-namespace when displaying the searchresults. Also you could directly hit "create page" button, because DW has formed a pagename from your searchphrase.
This behaviour is good and efficient for traditional Wikis, but bad when using namespace-oriented ones. So maybe it's time for a new option :-) I, for myself created a search-plugin which compensates this. It not only treat words as words, regardless of what chars used inside them (so even "
user@domain.de" is a valid phrase), but also shows the results in a way the user expected a searchresult. But, that's all because my users are no traditional Wiki-users, they use it as normal CMS or Informationsystem.