I guess my question is, why do people even bother playing the newer games or getting hyped for PS5/Series X when they already have their favorite so readily available?
Because you need to CONSOOM, dood! How else am I going to show off my new shiny-box-thing to my circle of totally hip friends!? I don't want to be that , you know, outsider or something, just because I don't have the latest new shiny-box-thing, do I?
Less sarcastic, general answer:
Honestly, the range of variety and creativity of that specific period remains unsurpassed to this day imo. I perceive it as probably the apex of creative video game development where budgets and pure creativity met at an intertwined, adequate level. I wouldn't actually strictly attribute it to the PS2 only though, its my general perception of the zeitgeist. The PS2 just happened to be the most dominant console of the period which manages to encapsulate this the most, probably because it attracted the largest talent pool. I think that most people point to the PS2 as being a better/best console purely by association and what it represents.