How important is it for you as a leader to organise social activities in your workplace? and how would that affect the prodcutivity of your company?

You certainly can, but it's usually better to facilitate employee-led activities. 

It's important to ensure that any such activities are inclusive and fair to everybody. 

Productivity benefits are likely to be modest.  However, there may be other benefits such as unexpected efficiencies, improved retention, better cross-selling, etc.

i can join as a friend and co-operate with theyers  in a workplace . so that increase theyer  efficency