We use wire ties for our zippers and we use locks on some zippers, too. Realistically all these do is slightly deter a thief. However, such theives are generally in a hurry and will likely select someone's baggage that does not have locks or ties.
Cutting the ties is easy and one or more of the following will do the trick:
(1) Use a knife from your hotel, condo, etc.,
(2) Carry a nail clipper with the file removed from it,
(3) Put your (dive) knife, Leatherman, etc. in a locked portion of your check-in luggage as opposed to a wire tied section,
(4) Put a small pair of dikes in your carry-on--I have never been asked about my dikes or my allen wrenches at security (Of course, that was all before September 11).
Jower