advantages of PC-relative addressing
One reason why PC-relative jumps are advantageous is that they require fewer bits. A relative offset might be just 8 or 10 bits while a full, absolute address might be 32 bits. So, relative jumps take less memory in the instruction code. Since typical jumps are nearby, using relative jumps also makes the code smaller in addition to the advantage of relocatability.

Also, the offset for relative jumps can be computed at compile time, while the address for an absolute (direct) jump needs to be computed at link time. This makes building code with relative jumps a little faster.