It's not a change in the rules.
The cost of creating an account is controlled by the witnesses.
They just haven't changed it yet because there has never been overwhelming demand.

Light accounts are not helpful, as they don't actually reduce the number of accounts required. They only change the UX for newbies and onboarding (IE giving control of the account to a centralized entity temporarily).

RC pools will actually make the situation worse as it gives all whales a financial incentive to lease their RCs at a profit and flood the market with them, push the price up for everyone else due to massive hyperinflation.

It is possible that custodial accounts could control more than one virtual account just like centralized exchanges do, but that tech doesn't even exist yet as far as I know... because there is currently no incentive to develop that functionality.