When is eval justified? In pragmatic terms, when you say it is. If it's your program and you're the programmer, you set the parameters.

You need to get out of the habit of thinking using quotes is ugly. Not using them is ugly! Why? Because you've created a function that can only be used interactively - it's very difficult to program with it. – hadley

If you need to call the function repeatedly, this is much, much faster than using eval.