The +2 influence points gives you an additional envoy every 50 turns which translates to +1.5 envoys at most until you unlock a T2 government. Completing city-state quests just supersedes that amount too much to become of significance in my opinion. But, it is better than nothing I guess. If you are slotting Equestrian Orders and you have 3 strategic resources, it translates to +10.8 gpt (at the rate of 72 gold for 20 strategic resources). So, 1.5 envoys or 810 gold? Maybe that gold helps you complete 1 or 2 quests you wouldn't have been able to complete otherwise?