If an SOIC fails, it can be easily removed with a hot air station, two soldering irons, or even desoldering braid. This is a major advantage over leadless packages, which often require specialized pre-heaters and stencils for rework.
The gull-wing leads absorb mechanical stress caused by thermal expansion mismatches between the silicon die and the PCB. This compliance reduces solder joint fatigue over thousands of temperature cycles. If an SOIC fails, it can be easily