Not giving junior lawyers exposure to senior business people harms their development. It helps them feel more engaged and more in the flow of the business. Most law departments suffer from the problem of top lawyers who hoard access to top clients, to put it harshly, or who fail to let lower-level lawyers interact with senior managers, to give it a more humane spin.
For the senior lawyer, wider-spread dealings by those below them lowers the ego rush of proximity to power and the felt-importance resulting from dealing with senior people.
In the longer run, it is better to spread the contacts. The solution is to try hard to bring in junior people to presentations and meetings. Let them step into the limelight in a variety of situations. There is a bit of performance evaluation that naturally goes with that. As a development tool, wider contact helps the law department improve.