I don't think the game railroads you too hard. If you want to stay within reasonable areas for your level....well it does. The quests haven't seemed to be too far out of your way for the main story line. With some determination though, it should be possible to just go wandering, that's what I did actually. I crossed over to Sloan (I think) instead of heading to Novac.
Hardcore mode is really the only way to play as far as I'm concerned. It adds a little challenge, but what it really adds is atmosphere. Not playing Hardcore mode, and your character is like a tank with Stims fixing broken limbs and never needing food or sleep.