Removing filler words from normal speech gives you clearer speech, not a sermon. Orators use far more tricks than avoiding filler. They speak loudly with exaggerated tones. They
exude emotion. Oration is a performance, and for most people it does not come naturally.
It's easy to see the difference with examples. A good example of clear speech is Sam Harris. Even when debating contentious topics, he speaks in calm paragraphs.[1] I could imagine Harris behaving the same in a one-on-one conversation. Contrast that to his opponent, William Lane Craig.[2] If Craig spoke that way in my living room, he would appear insane.
Avoiding filler is necessary for oration, but it's not remotely sufficient. I think this app will improve people's ability to communicate, not bloviate.
1. https://www.youtube.com/watch?v=yqaHXKLRKzg&t=3556
2. https://www.youtube.com/watch?v=yqaHXKLRKzg&t=4226