Like many pagan and earth spirituality rituals, the I-Groups begin with casting a circle of sacred ritual space. Then an invocation is given to call in the spirits of the directions (Calling in the 7 Directions – east, west, north, south, up, down and within) and any other spirits that may be important (grandfathers, etc.).

Thank you for acknowledging the value in this practice – i.e., creating sacred space. Opening ritual is also effective in getting men out of their heads, and into their bodies. It is a very effective call to presence – regardless of the spiritual or religious beliefs of men.
The work that goes on in weekly I-groups invites men to touch their feelings; which requires that they be aware of what’s going on in their bodies. Feelings are a gateway to awareness, which is a necessary first step before any personal growth or healing can occur.
Every religion and spiritual tradition recognizes the value of ritual. The ritual you refer to is borrowed from native American traditions. Native Americans cultivated among their people an intuitive understanding of their place in the cosmos; and recognizing the spirits or grandfathers from the seven directions was/is an integral part of that understanding.

I suspect for some of the initiates, this is regarded as a formality with no thought that any real spirits are being or even could be summoned.

Coming from a Christian background, I initially found the calling in of spirits/directions a little offensive. However, as I began to understand the value of spirituality (particularly native American and/or pagan spirituality) vs. religious dogma, I gained a real appreciation for this tradition.

However, in reading stories and accounts written by MKP writers and leaders, it seems to me that some of them take this more literally.

Your arguments would carry more weight if you were to be more specific about your sources.