There is nothing wrong for management to communicate its employees to follow one pattern of languge as a medium. And I welcome that. If every individual speaks in the language of his own, then there is no uniformty is maintained.
When office circulars, inter office correspondences, Office Orders are all in English, why not we insist English also as a language in a common platform. When someone is habituated to speak in Hindi, Tamil or vernacular, they will start communicating in the same way when others are sitting next to him/her without realizing that the other one does not understand his/her language. This gives room for the third person that these two want to hide some matter from him/her and the reason why they speak in vernacular, though it might not be the case.
Secondly, every language has got its own accent. You cannot imagine something in Hindi and start conveying in English. When someone practices in office speaking in Tamil, when sudden situation of switching over to English arises, he will land up in speaking "Tanglish". They blabber and not able to use correct vocabulary. This may be OK within small group. But, assume such people need to give a presentation to a elite group of people from abroad. He represents the company and not as an individual.
Moreover why someone has to think that it is a "forceful" acvitity. Practice makes a man perfect. One can look at this situation as a positive approach to "sharpen / hone" his English speaking skills. It all depends on individual's mental framework
V. Balaji