To vary the unit entitlements needs anew survey, a current valuation to apportion the unit entitlements and the help,of lawyers. Who is going to pay these bills ?
The law does allow for the adjustment of UEs but, as Kaindub points out, it is a complicated and expensive process. As a result, it tends to be the most egregious distortions – where one owner benefits to the disadvantage of the vast majority of other owners – that are corrected. An example would be where the developer has kept the UEs for a large commercial lot, or a penthouse apartment, low to attract buyers, meaning that all the other owners in the block effectively subsidise one or two owners.
It is not financially or micro-politically feasible to tweak UEs to make them a bit more fair for some owners.