If you only race, or drive in Phoenix in the summer, you don't need a thermostat. For most every other circumstance the thermostat will prevent over-cooling of the
oil. Cold
oil doesn't flow well or provide optimal lubrication. It is also slow to drive off condensation. A combination of higher viscosity and cold
oil is also very tough on the oil pump drive on the distributor.
An option is to plumb "dummy" lines on the cooler for now and you can add an oil thermostat and "live" plumbing later.