One of the very good reasons for insisting on special resolution approval for changes to common property is that the law demands that the Owners Corp addresses the question of who is responsible for the Common Proprty thereafter.
The default position is that the Owners Corp is responsible but it clearly allows, if not encourages, the General Meeting to make the person benefitting from the changes responsible for ongoing repairs and maintenance.
This is what the Act says:
Division 4 Special provisions for by-laws conferring certain rights or privileges
54 By-law must provide for maintenance of property
(1) A by-law to which this Division applies must:
(a) provide that the owners corporation is to continue to be responsible for the proper maintenance of, and keeping in a state of good and serviceable repair, the common property or the relevant part of it, or
(b) impose on the owner or owners concerned the responsibility for that maintenance and upkeep.