Most of the time people tend to use the suit and tie approach when going to events/ trainings/ presentations for which they have no clue as to what is going on. They have the impression that if they do that they will immediately seem focused on whatever it’s going on.
From the same dress code you will also have company representatives sent to promote the interest of the firm and network. The problem is that when they network they will try to find someone matching their presence and most likely they will end up interacting with the people they have no idea why they are there.
On the other hand, the people who are really there for the action/ information/ presentation don’t need to do that. They will match the even with the attitude they bring, the interaction they create, the knowledge they possess. Most of the time they are dressed casually since their focus is on what’s going on and not on the image they reflect.
If you are going just to network and present an image to others around then suit up, but if you are going for the action and the information just make sure you are comfortable and make the most out of it.