Well, I won't be doing this either but I can see why it could be attractive to some. For example, if you are struggling to stay within budget every month, an app that analyses your spending and shops around to present you with better deals such as lower broadband or energy costs, even deals at the supermarkets could make a difference to a struggling family. It may make the difference between staying out of debt or applying to a payday loan lender.
There was a recent thread asking how much people spent on their weekly shop. If you want to trim your expenses, one of these apps could help.
Yes, there are risks but we've all been allowing direct debits for years. If you've never used online banking, you may not realise that you need more than a password and PIN to set up payment from your account. Certainly, this information should only reside in a protected system, you should never give it to a real person.
It may be a silly idea, only time will tell but there may be benefits.