Things of quality should be built up and worked towards, not thrown together and forced to allow for interaction. This is a sandbox RP. Done right, there should be a blend of both solo arcs and collaborative efforts between players. 

For example: Gowi and I will have several collaborative plots in the near future, but we are both currently doing primarily solo arcs to better develop our characters and the part of the world/RP they live in. If we had just decided to do a collab post immediately, solely for the interaction, our characterizations would likely have suffered.

All-in-all, I believe interaction should be well thought out, otherwise you end up with another debacle such as Robinson Park - to use a reference the Ultimate RPers here would be familiar with.