Seriously, yeah. If everything in a game you can do just as amusingly in Runescape, play Runescape. But that's simply not the case. There are vast, vast amounts of games that are nothing like Runescape. Can you manage resources and dwarves to fend off attacks while maintaining a food supply and even engraving/decorating lavish noble rooms in Runescape? Can you evolve a small bacterium to a civilization spanning many galaxies in Runescape? Can you enjoy FPS-style team battles with diverse weapons in Runescape?
That being said, I do find Runescape pretty amusing for a few hours until you run out of the free quests. I especially like the complex craft system.