I don't think small planes are dangerous on their own, they are just used in some operations that carry more risk. Landing on a sand bar in a river in AK to deliver mail involves more risk than landing at ANC. Pilots flying light twins often fly into airports with either a non-precision or no approach, at night into black hole airports that may not have vertical guidance information, with short, narrow runways that may be coverd with snow, ice, or wildlife.

There is no excuse for not being safe, but things can reach up and get you quick, so you have to be on your toes.