It's an extremely poor venue for rugby league.
For over a century, it was the only major sports arena in the Sydney metropolitan. That's why it's tied with rugby league heritage.
The move to SFS in '88 was a quantum leap for spectating rugby league and any other rectangular arena sport. The downside of the SFS when it opened was its capacity and that limiting BS spacebowl design by Phillip Cox. There may have been space concerns due to the northern end of the ground being a strong piss stream from Moore Park Rd, and likewise with the southern end and the SCG, but new Lang Park rectangular type design with a 2nd tier right around the ground would have been ace. I think there may have been issues at the time with maintaining the SCG as the biggest capacity venue in the metro, too.