I get the whole "this is my device; I paid for it; I should be able to do whatever I want with it" viewpoint. I agree with it, as long as those of us rooting (myself included) acknowledge that we're voiding the warranty and we take full responsibility for anything that goes wrong because of rooting.
I think they don't want people rooting the phones, screwing them up, flashing them back to stock, then trying to get them replaced under warranty or insurance. Even if Moto doesn't have to deal with insurance claims, it still affect them when reports show that they have a high number of claims on their devices. It makes it look like they're releasing crappy, defective products and it could steer potential customers and carriers away from their future products.
As for whether I'll get the X, I might get one for wife, but I'm waiting for the beasts coming out later this year or early next year. I root primarily for overclocking. If I had a 2Ghz beast I wouldn't need to overclock. I don't need to theme; I'm content with the ability to choose my wallpaper and I already have the ability to use custom icons and launchers without rooting.