Has Nexon ever successfully take suggestions from players?

They have, yes. Usually, though, these things only have an impact if it's suggested on an open forum, such as real life events, Twitter, the official Nexon forums, and stuff like that, where you can actively get a Nexon employee's attention. Moreover, these things can only be taken as possible suggestions if it's a thing that's a logical move for the game and not just a random suggestion just because it sounds cool.

For bugs and whatnot, try getting a Nexon employee's attention directly, or get a mass group of people on the case in order to get their attention.