This is how I see it: I use blockchain.info and I love it. But I don't store all my bitcoins there. I like to spread the bitcoins in 3 or more different baskets, the more I trust a basket the more bitcoins I put there. My offline wallet has the most.

I think it's the same with NXT. For a newbie, that just wants to start using NXT, I think the online wallet is perfect. If you own several thousand or million NXT, I would not recommend putting all of it in the same place, be it the online wallet or a single NXT NRS wallet.

But you could put some in the online wallet in case you need to use them on the go, or at work, etc.. this is how I am going to use it myself.