Debounce: yes!
Filter short duration spikes that are nothing to do with contact bounce: no, obviously.
If, in a given application, the switch inputs are prone to noise pick-up, then I agree that a timer is a good way to filter those. I've not personally found this to be a problem, but perhaps if the switches are remote from the processor then it would be more of an issue.
Of course, in that case, you'd probably want to include an ESD or other transient suppressor near the CPU anyway, and possibly a current limiting resistor.
Either way, I don't think it's good to have an inherent response delay equal to the worst-case contact bounce time. Noise spikes would - I'd expect - tend to be much shorter in duration, and could be filtered with a much shorter time constant than would be needed for reliable debouncing.