Basic wage are considered as fixed income and can affect many compensation qouta, of which one as you say is the leaving service benefits and gratuity payment calculated as, year of service multiplies last drawn basic salary. Allowances on the other hand are normally non fixed and can be revised and reviewed at anytime. Given the above scenario, its no wonder that employer choose to increase allowances of which they will have no documented commitments in future.
Basic wage are considered as fixed income and can affect many compensation qouta, of which one as you say is the leaving service benefits and gratuity payment calculated as, year of service multiplies last drawn basic salary. Allowances on the other hand are normally non fixed and can be revised and reviewed at anytime. Given the above scenario, its no wonder that employer choose to increase allowances of which they will have no documented commitments in future.