I think it is important to realize that optimum tick size is not just a matter of making it as small as possible. This is because tick size has a real influence on the time priority rule.
When tick size is trivally small, the cost to obtain price priority is also small, and this decreases price competition. On the other hand, if the tick is too large, traders are hesitant of improve prices because of the increased cost of entry.
As a result, setting tick size is a balancing act for exchanges to which they pay careful attention; and it is misleading to ascribe larger tick sizes only to the desire to placate large or influential trader/members.
When tick size is trivally small, the cost to obtain price priority is also small, and this decreases price competition. On the other hand, if the tick is too large, traders are hesitant of improve prices because of the increased cost of entry.
As a result, setting tick size is a balancing act for exchanges to which they pay careful attention; and it is misleading to ascribe larger tick sizes only to the desire to placate large or influential trader/members.