As a guest, would you be utterly lost and confused if there were no announcements made by the dj?
Guests can usually figure out who the bride and groom are, when things are happening (dinner being served, dancing starting based on music played, etc) and so on. As a guest at weddings/anniversaries I've attended where there was a dj, nothing was really announced at any point and guests were able to stay on the dance floor, figure out when dinner/appetizers were served, etc. Would this absolutely confuse the crap out of you to not have every single action announced or is an MC vital to your guests enjoying themselves and knowing what is going on when instead of going with the flow?