People don't use it because it's too far away, it's practically useless. The only time people use it, is if they're using somebody else's phone and don't want to bother looking through the folders and pages.
Imagine if you in an app and you want to search for something, you have to tap on the Home button once, then tap on it again to go to the first page(If you aren't there) and then tap for the third time to switch to Spotlight, instead of doing all that most people just resort to scanning through the homescreen or just opening the app they want to search in and getting the information that way.
Spotlight, and search basically should be right under your finger tips, easily and more importantly, quickly accessible anytime you desire. That's why Spotlight should be integrated into the Notification Center, above the widgets.
That way, if you're in an app and want to search for something on the web say, you quickly pull down the Notification Center enter the search and tap go, the app will instantly switch to Safari and you're searching...
I've suggested to it Apple through their feedback page multiple times, I hope they will put Spotlight where it is supposed to be.