Compression vs Tension?

On various plans I've looked at that use truss construction (4130 fuselage rear section for example), it seems the tendency is to design most diagonal bracing to be in compression rather than tension, providing I'm correctly seeing the direction of potential loads. In doing some simple math (all I'm capable of), it seems that a smaller cross section or thinner wall tube could be used for weight savings since the tension capacity seems to be greater than the capacity of a given tube to buckle under compression. Is it somewhat to reduce the potential for a weld not holding on a tension joint, vs the compression joint not being reliant on the strength of the weld?

Just curious.....

Lynn