A firm's management should consider doing these things because personal relationships and connections can be very important in business, even when business is conducted across national borders.
By going to trade fairs or, especially, on trade missions, the management of a firm gets the chance to meet important people from other countries. They might meet businesspeople with whom they might make deals. They might meet government officials from whom they will need permits. In many cases, these people in the foreign countries will feel more comfortable and confident dealing with people they have already met in person. This can give the firm a leg up in competition in a foreign country.