I'm not sure I think it would be a bad thing if proprietary software licenses stopped disclaiming all liability, but there's no evidence that creating liability

I'm not sure I think it would be a bad thing if proprietary software licenses stopped disclaiming all liability, but there's no evidence that creating liability for data breaches (for the entity that collected and stored the data, not whoever wrote the software they used to do it!) is going to change that. Plenty of companies already use software in ways that creates liability for them, and yet as you say shrink wrap software rarely comes with any warranty. Individual liability seems much less likely to me, in the absence of statues explicitly forcing this liability onto individuals. If you are a consultant, and the market equilibrium actually shifts so that customers are demanding security warranties, your insurance costs would go up, but unless you are less competent than average your equilibrium income should go up to match. The legal incidence, and plausibly the economic incidence, is all on companies that actually handle personal data.