There is obviously a security trade-off with using brain wallets, but soon some bright spark will offer a public facing node with some added security features on top of NXT. Once that happens regular people (i.e. not hard core crypto freaks and computer nerds) will naturally go for the most user friendly crypto that has achieved a stable subjective value among its users. That will be NXT.
Bitcoin and the others are just too difficult for regular people to use.
NXT is easy - just go to a public node and enter your password.
My grandmother can use hotmail, and she can use NXT too. She couldn't download and install a crypto client in a million years.
In its current form its not that easy to use. Install Java, extract nxt.zip, run a special command line command or setup a batch file, hope that it works.
NXT is definitely not ready for the casual user.
Personally, I would never use my account on a public machine. That is a disaster waiting to happen.