Ranking based on a number of factors, not just a string match is generally a good idea.
When someone searches on the term "maps" do you want the "best" (highest rated, most popular, whatever) app to be the top hit (give it a week and that'll likely be Google Maps), or the one from the person who had done a bit of SEO and thought to call his app "maps" to hit the exact string match?
I contest that what's happening is actually a good thing and what you propose would be a field day for those who look to game the system.
Does that hold true when the exact string match is already #1 on the Free Apps list? Because to me, if it's an exact string match, AND it's wildly popular...
Okay, how about, it's an exact string match, it's wildly popular, and it's from a well known and long time developer whose apps have always been wildly popular? Is that enough yet, to make search not suck?
PS, Google Maps is now the third search result instead of the fifth. After how many days should search not suck?
Given that that app is going to be there for years, how about what percentage of the time? At the moment it's likely that it will be a small fraction of 1%.
And search doesn't suck - it's still easy to find, you just need to look a little bit more. Given that it's the number one free download discovery really doesn't seem to be an issue here.
First five results:"Google Earth", "My Places for Google Maps", "My Maps Editor", "Road Tripper", and then finally "Google Maps"
Seriously, how difficult is it to bump an exact string match to the top of the list?
Seems to me that iOS is just getting worse and worse.