I think BA would prefer the policy it currently has. After all, the bulk of Golds and Silvers travelling in J will be on fares comparable to that being paid by the OP's colleague. The bargain-basement I class ticket holders and award redeemers so often seen here aren't representative of BA's higher tier membership.

After all BA has this policy, it has had it for years, and it's clearly maintaining it.

You'd prefer something else and you'd like to project it onto BA, but that doesn't mean that BA agrees with you; clearly, it doesn't.