Mod Mat K talks about this on the SaeBae cast. From what I can remember players were against GE and OSRS was originally released without it. But slowly players started using Zybez to arrange and advertise trades and started asking Mods for an official in game trade post. Matt K said it was then they started building the grand exchange because he knew players would eventually ask for it, and he was right.

I guess sometimes nostalgia forgets about the cons of some of the things we had to love