To be honest, this is something I would say to my boss when he brought up that he was going to use a system like this for standups. "Hey, why spend 14 bucks a month when I could build this in a few hours? We'll just write a cron job then cc everyone in the team.."
First off, there is probably a lot more to a system like this then you think. What happens when you need to add people to the team on the fly, or change the format of the email? Do you want to be the person who has to maintain this system for the foreseeable future? Is this what you really want to be working on?
It's a cheap bet that could shave off a few hours a week of work. Our standups can take up to 30 min each morning for our team if there are a lot issues from the pervious day. I rather have a 15 min standup and have time to prepare my questions the night before, or on the way to work.
It's hard to justify new systems like these when as engineers, we are conditioned to build our own tools when we see repetitive tasks that need to be streamlined. Personally I would love a system like this. It would save a lot of time for me each morning. On the other hand, I could see this going to the company graveyard of dead tools after someone finds a new system they read about on HN.
Agile practices can sometimes turn into Show & Tell time when people don't succinctly sum up there issues. Making people think about what they are going to say before they bring up blocks and issues they are having can definitely save time each day.