They can. Think of putting thousands of hours, get those rare items, awesome drops, and wake up to find some jerk has taken it all. Its kind of like those "type the word you see" crap on websites.
Whoa, scary. Makes me wonder if I should bother now.
I know it's happened with FFXI (gil farmers were always a blast too..), so even with the app for your ios devices, Android, or if you have a security token (from the CE, or from FFXI), it doesn't hurt to use it just in case. Granted, PS3 players should be less susceptible to it unless you give your account information out (which is a nono), but Sony did get hacked, so SE could as well.
Now in HD: Courage is the magic that turns dreams into reality. Dragon Quest>Ys=SMT=Tales>Final Fantasy, but I enjoy all five.
If you want to make it MUCH HARDER for your account to be hacked, this token will allow you to have a second password that changes every time. The only way to figure it out is supposed to be with the keychain or iOS/Android app.
If you don't want that, don't add it to your account, but don't cry when you log in one day and everything is stolen and you have to wait for the customer support to help you out. It doesn't happen to everyone but it does happen a lot. There is real money to be made here and there are bad people who will do anything, including steal fake, digital items and money from you.
The best solution would be for people to stop freakin' buying currency and items with real money from third party sites. That's what makes accounts worth hacking. Not that some people don't do it just for the lulz. Some people really have nothing to do but ruin other peoples' lives.