If you’ve been following this breach, the key problem here is two part:
1) TJX is the parent company of several other companies including TJ Maxx. Each of those companies shared data with TJX creating a massive database (and a single target for the hackers).
2) TJX (and others) shouldn’t have stored the credit card data in the first place and when they did, they should have used better security.
Though they’ll blame “clever hackers” for the breach, the fault instead lies squarely with TJX who’s business practice of storing credit cards against people’s will along with negligent use of outdated wireless encryption (WEP) first created a giant target and then then left a gaping hole for the bad guys to be able to go and get it.