RO definitely was fun to grind in, to the point it's hard to resist cranking up a personal p-server just to mash some prisoner zombies now and then :P
The idea is pretty simple, actually. Originally the level itself didn't mean quite so much, it wasn't just a statistical number you flaunted on the forums that looked especially impressive beside a string of more high numbers. in FFXI for example, being a first generation 75 still playing years down the road meant you've experienced so much of the game, were part of the community for so long, and were a pillar of it. Yea, surely you can be a part of the community regardless of the level model in a game, but take FFXIV as it is for example: Who would you go to for information on a class? Everyone has similar experience, not because they choose to have that experience, but because you have to to have a 'good character.' I have no incentive to trust anyone on these forums for advice as my favorite roles.
Being a career WHM 75 meant that you generally were a good person to talk to for a noobie wanting an idol or simply someone wanting pointers on healing. In a game like WoW, asking an 85 might get you an "i dont know lol" because in truth, they really dont know and don't have to know. In FFXIV, you don't have to know much beyond how to properly AOE, which, really, does it take 8 years of college to achieve? Time involved in a class really used to meant a lot of knowledge, especially for the not-so-obvious goodies SE tucked away for pros to figure out that new players HATE so much now. Sort of like being a town elder, but more nerdy. And this isn't for epeen or brag rights, it came naturally, because the community was small and close.
I don't feel necessarily callous to the casual players and I certainly do feel they deserve a fun game. I doubt anyone is out to make casuals have less fun. This is why it's imperative for lower level game content to exist for them, rather than design the ENTIRE game around getting casuals to 50 to feel whole.
PS: The reason being a single 50 means nothing is because games have made it feel like it should mean nothing. Being max level used to be a full time job in a game!