I think that if you can take the pedals with you when you upgrade, then there's no reason not to get them now. OR, there are those $7 toe clips that you could put onto those pedals there.
A note about the *mart bikes. When I was about 16, I got a Schwinn 10 speed, and man I rode that thing for the next three years all over the place in all kinds of weather, and I loved it. Heck, I probably did a couple of centuries without ever intending to, all without Power Bars or Super Goo Gel or $80 t-shirts - wow!
I think those bikes are a very good value when you're starting.