Just like everything else in life there are pros and cons to incineration.
It is the best way to sterilize.
It can break down some toxic waste compounds.
It has a good waste reduction ratio.
It may be possible for the combustion to produce enough heat so as not to require fuel.
The ash may be difficult to dispose of as it may be prone to leaching toxic compounds.
Scrubbing the exhaust is becoming more expensive and difficult.