But the advantages are - better for compliance, faster analytical queries, possible to upgrade people at different paces. I agree it would be painful from a database migration perspective but I can see situations where it might be the right call.

I have read about table inheritance but never used it. It seems like it would make it possible to alter the schema of the root table, but it probably introduces other issues that I am not aware of. You would still need to manage indexes, constraints and default values for each child table, but the structure of the table itself would be inherited.