I agree with Gerhard it’d be nice to have notifications dismissed. I get notifications while I sit at my computer working. By the end of the day I’m apt to have 50+ notifications on my phone. All those notifications have been dealt with already, however, via my desktop.
Email seems to me like a totally different beast. We don’t have complete control over the email process. Everyone’s email provider does things differently, there’s no standard for knowing if someone read an email (read-receipts don’t count).
Unlike email with the app we’re dealing with 2 standards: Google’s and Apple’s. As long as we follow the standard that’s in place clearing notifications should work.