Here is my idea: remove retainer leveling.
We already pay for the retainers and I think that the idea of having the option to pay to level them up on top of it is ridiculous.

Or...instead of having a retainer level, give us a "Retainer Owner" level, so that we just have to level up once and then the level cap applies to all our retainers.
(Now I know people will come and say "SE is a business, they are here to take money". To that I say : whatever.)