It's possible that the traps were meant to serve multiple uses...
Allow Dumbledore through, without too much hassle.
Slow-down - rather than stop - someone trying to get the stone, so that Dumbledore could be notified (wards) and had time to intervene.
Serve as test for Harry Potter (whom Dumbledore knew eventually would have to be the one to stop Voldemort) and his friends. If so, it makes very much sense to only use the teachers teaching 1st year subjects. (In addition, Hagrid conveniently gave Harry a flute for Christmas to put Fluffy to sleep.)
Make sure no one teacher could easily disable all traps using their own expertise.
Test the teachers' loyalty, by seeing how difficult their traps were (eg. Quirrel's troll).
If Dumbledore just wanted to keep the stone safe, why use a simple locking-charm that several students (including 1st year Hermione) could bypass?
If Dumbledore wanted to keep the stone safe, why not bury it under the stone-floor of his personal quarters (accessed through his office, protected by a gargoyle) and use many layers of wards?
Why tell all the students at the welcome-feast, in a way that almost guaranteed some students would try to find-out what was hidden?
The only real safety-measure was the mirror, as someone who wanted to actually use the stone, would spend hours trying to get to it... assuming they didn't also succumb to the magic of the mirror, and "wasted away in front of it".
So I would think everything but the mirror were just slow-down an intruder, and to test Harry and his friends. If Dumbledore wasn't away, I'm sure he'd observe Harry's journey through the traps - maybe he did.