ksocrat (GPL) depends on ksocrat-data (non-free);
ksocrat works only with ksocrat-data;
ksocrat-data license allows to use it only with ksocrat.

Hence it seems reasonable for ksocrat-data to depend on ksocrat in its turn.

Pro: reduces user confusion
Contra: creates yet another cyclic dependency

for me, seems that "pro" is more important than "contra" here. :)