I am asking the same question myself. My new trailer has E-Z lube hubs that only needs a shot of grease once a year? Probably the main benefit of removing the drum is to inspect the brakes not grease the bearings.
I probably will continue checking brakes every couple of years or before any "major trips" thus saving the cost of 4 new grease seals.
I have, in the past, found broken shoe retracting springs that were previously undetected. There was no symptom of malfunction, no noise, no pulling to one side, no wheel lock up. Only an inspection revealed the defect.