Imo, the way the map is structured in ToS is closer to Granado Espada (IMC’s previous MMORPG), where you’d move from one map to another based on your characters’ levels, than RO. You’d stay and quest/grind in the same area until you were high level enough to move on to the next area. At least, that’s what I recall from when I played GE. (Yeah, I admit it was overly linear and boring to me.)
Also, this far in, I agree it’s too late to make major changes to the game (making it “true open-world”). Some maps are way too tied to the game’s story (like the one with the vines that the player must burn down). Like @njkooper mentioned, I think the most realistic solution now would be to add lots of optional/hidden areas to make the grinding spots (and/or exploration) more varied.

. As a noob crappy looking acolyte when u watch other PRO players u’d have this feeling that u want your toon to be like THAT so u work hard to achieve it as it grows. In comparison to games like AION…your toon character already look dashing starting from level 1. Theres not much satisfaction there.