Seems to me, suspending a driver for one race is a greater penalty than suspending a crew chief and some crew members for four races.
My reasoning is, the whole team (including how the car performs on the track) revolves around the driver. His "feel" determines how they tweak the car's handling, and tailor the motor's throttle response, and other things that effect how the car performs. His driving talent and decisions determine how the team runs their race and usually the outcome. The driver is also the sponsor's public interface, and can determine if the sponsorship money continues or changes (it can even go away).
Not discrediting the crew chief and other crew members - they are important too - but they have much less public exposure and less individual impact on race results. They can be (and are) more easily substituted with less overall impact on results. When they are suspended the team will probably not perform as well as it could otherwise, but it usually performs better than when the driver is suddenly replaced.
Driver suspensions are also a penalty to NASCAR. They effect its public perception, which eventually translates in the Series' popularity and marketability. Of course some drivers impact this more than others (such as NASCAR's ongoing slump since Big E passed away), and some fans may celebrate the absence of certain drivers, but to the general public these things hurt NASCAR's credibility. Yeah, many say that the fight at the end of the 1979 Daytona 500 rocketed NASCAR's popularity, but it did so while imposing a stereotype that limits its growth.
Wallace deserves suspension for his dangerous retaliation on the track. One can make a good argument that his suspension should be longer. His walk down the live track, followed by his slappy fit on Larson, was only dangerous to himself and it made him look bad. He only hurt himself by doing that, and placed a target on his own back. But particularly while NASCAR still apparently fosters its redneck-trying-for-diversity stereotype, NASCAR doesn't need Wallace on the sidelines too long. Wallace brings public attention, and with it marketability.
