I take a more cynical view than you both. All decisions made by clubs are either directly of indirectly to increase revenue.
Directly, they buy replica shirts to sell for a profit.
Indirectly, they invite the local schools in free hoping the kids bring paying adults, or come back as paying customers themselves. This ends as soon as a negative, or even passive result is indicated on the balance sheet.
Pitch hire, saves outlay for affiliate clubs and reduces the need for the parent club to subsidise. Non-affiliate clubs or customers pay the going rate.