The key word here is Trust
I can think of two common cases where changing a topic title is appropriate.
A new(er) member posts a less than accurately descriptive title. eg.
"Please help me with this"
Such a title does not convey what the topic is about so it would be justifiable to edit it to something better eg.
"Need help understanding Profile Preference Settings"
Another common case is misspelled words. Though I imagine most humans can figure out what was meant, automated Search isn't always so intelligent. eg.
"Howto: Stting up an email servere"
should be edited to
"Howto: Setting up an email server"
I guess some people might be more the "spelling / grammar police" type and feel an urge to "polish" titles, but I would hope that such an urge would be generally suppressed.
That is, that most having the capability to edit topic tiles would not assume the role of "proof-reader" or "copy editor".