Yeah, I can see a good argument for putting it on by default, and perhaps 60-planet maps, which are really better for a first-timer. That said, I can see wanting to communicate that those aren't the "standard" options, so perhaps just add a message somewhere suggesting it?
I'd suggest trying some really small maps; I've been playing 20-30 planets lately and I find them really entertaining. As X says, it's a cage match; takes less long-term strategy but you have a lot less room for error and you have to do a lot more with less.
EDIT: Sorry, that last bit for Khan, not OP. 20-30 is pretty hard unless you're used to the game.