Public prayer is not a communication with the divine. No sir, totally not. Personal prayer is arguably so at some time, but prayer itself more often is nothing with god other than what they try to believe.
For a thing, the All Knowing already knew, and other than long words, pure feeling of gratefulness or hope will be enough.
Prayer thus, when performed alone is a self-reassuring. You’re telling yourself hopes and motivations. In other time, you remind yourself again what you should be doing to fulfil that wish.
When performed in mass is a public communication method. Most easy to see case is the Intercession in my opinion. Prayer in behalf of other is not to be heard by god, but by other members to tell them about a situation of fellow members in trouble. In ideal situation, this should raise awareness for the community to help and support each others. In modern days, the effectiveness varies but usually questionable.
In more humanistic culture, large rituals is also not for those Above. It works as a reminder to the teachings, re-doctrination if you prefer, but somewhere along the line. When seen as an organization, religion should have a method to keep the common base and strengthening its foundation right?
Is it bad and we should stop prayer? Probably no. Although, for some peoples, thinking that it’s a worldly activity without miraculous effect might even made thing worst rather than perfecting it through understanding of the system working underneath.