first, its business. less games, less brand exposure. instead of paying a page (print) or spot (web) to promote or advertise ta brand, the news about games (pre and post) does it (among things).
second, its business. pba companies in general are not as rich as companies in most other countries. they want to maximize their investment (why pay for a full year salary when they only play 6 months? they might as well maximize it, 9 to 10 months).
third, its business. while eala then was able to come up with a 2-conference a season to allow break that fits d fiba schedule but still provide more pba games, d pba teams were able to correctly point out that its not about more games, but more playoff games (which will be d case in a 3-conference format) that brings more fans interest and media mileage. more conference also means more chances for teams to salvage a season (for example meralco who is used to being bad or very bad in d first 2 conferences, but very good in d 3rd conference).
moreover, d eala format was used for a number of years and d results were not really encouraging, we still sucked then.
in the end, the pba schedule is this way because of the type of business model that they have adopted. and it is this business model that put food in d table of hundreds of players and their families. sbp will not dare go against it. especially as the current sbp people are current or former pba officials.