With FileVault, you don't even have the protection of backups if FileVaut breaks!!!!! If you didn't back up with FileVault, it's not secure, so what was the point in the first place??!?!?
For the truly paranoid, the backup disks can be FileVault protect too (or some other encrypted method, such as an encrypted disk image on an external disk, or the backup utility encrypts the backup data before sending it to a remote backup location).
NOTE: Since FileVault 2 has been released, there have been almost no problem reports for it. At least not in the forums. The worse that has happened is forgetting encryption keys, which is devastating for the user, but that just means FileVault is doing its job very well.
I think I'm hearing that your sensitive information is not the kind of info that someone would spend money trying scavenge from your disk/SSD free space nor spend even more money to recovery information from replaced sectors.
You could most likely protect your sensitive information by using an encrypted disk image, storing it in a KeyChain secure note, or using something like 1Password secure notes (or other 3rd party encrypted password manager with secure note capabilities).
But just be aware, that these methods can have leaks that someone with money to burn and a strong enough desire to see what you are encrypting might be able to recovery from temporary files, deleted files, replaced sectors, etc...
On the other hand, I have seen lots of stories of people buying systems or disks from eBay and finding all kinds of personal information that would allow them to impersonate that person sufficiently to gain access to their on-line accounts, including banking, and other places their money is stored. This would not happen to anyone that was encrypting their whole disk.
But from Apple's perspective, these information leaks because secure erase cannot get every bit of data that went into creating the file that is being erased, they have a liability problem from the people that really do need to make sure all bits of that data are erased, but do not really understand how the applications they use work with the data, how the file system does its job, how the operating system pages/swaps data to disk, how the disk itself moves the data around, etc... And that today most of Apple's shipping systems are SSD based, which suffer reduced life from secure erase without even touching the original data. With all of that in mind, Apple most likely decided it was better to remove secure erase than pretend it was doing anything.
NOTE: In my opinion the only really secure erase is to take all the things that might have had a copy of your data, and melt it down in a very hot furnace until it is puddle of molten metal and plastic. Of course I've never actually done that, but I'm sure it is secure.