Security products are a hard sell. And, there's a lot of snake oil and voodoo that gets passed off as useful. One of our competitors had (maybe still has) a slew of security issues, existing for years, and yet people kept buying and deploying the product at an alarming rate (it was extremely cheap, and had a tremendously long feature list)...it took a disaster at the company to change things to where we no longer view that product as a real threat in the marketplace. But, I never could figure out how people could overlook the abysmal security record.

Security is sort of an amorphous concept that most people just can't really wrap their head around. What does secure software look like? How do you know it's secure? Non-technical users have no way of knowing; expensive software is just as likely (if not more likely) to have security issues as Open Source software. Software that claims to be secure can be just as insecure as software that makes no such claims.

Security is a process not a product. You can't buy security. Things like proxies, mod_security, firewalls, IDS, etc. are all bandaids that you put over problems, and they're usually "preventing" ancient exploits that have already been fixed in the underlying software (assuming you're running the latest version). They might prevent some attacks, but if you're running insecure versions of your software underneath, a determined attacker will find a way in.

In short: Security is hard. The new hotness is easy and is an easier sell.

I think there will be increased demand for such a thing, but the security features a secure PaaS could provide (network and application firewalls) are never going to be a 100% solution. There is no substitute for building your product securely and no PaaS will do that for you.