There are many times when a roll call leads to a more effective meeting:
1. The meeting leader may have received apologies for someone in advance who might have sent a deputy.
2. When introductions are necessary; perhaps a new person is joining a regular meeting, or possibly a you have a guest come to present their ideas/product for part of the meeting.
3. You might like to remind people that a particular person is part of the meeting who's first language is not the language of the meeting.
4. You might like to remind the team that your boss is on the line this time by exception!
As leader you should know who is there. The roll call is not for you, it is for everyone else, analagous to looking round a meeting table. People will be more willing to participate if they are sure who is taking part.