For you it may be a low risk. For Apple its not. Apple will be shipping millions of machines.
And these machines are already vulnerable just to single bit errors anywhere both in the IO path and in memory.
The repair-of-death you describe involves multiple errors in the memory path occurring in a specific order and in relatively specific places, that are already dangerous to existing filesystems.
The atime update metadata corruption you quote is similarly already a problem with existing filesystems. In fact it's more of a problem for these filesystems because they're overwriting existing metadata, not creating new copies of metadata that can be rolled back in a disaster as ZFS does.
Even if we take it as true that ZFS is more vulnerable to these specific types of error (by no means demonstrated), that needs to be balanced against all the other errors it's less vulnerable against.
Stop approaching this from the perspective that ZFS is flawed. Rather approach this from the perspective that ZFS assumes memory can be trusted
... so does every other filesystem. I'll quote another bit of that paper you like:
"In addition to ZFS, we have applied the same fault injection framework used in Section 5 to a simpler filesystem,ext2. Our initial results indicate that ext2 is also vulnerable to memory corruptions. For example, corrupt data can be returned to the user or written to disk. When certain fields of a VFS inode are corrupted, operations on that inode fail or the whole system crashes. If the inode is dirty, the corrupted fields of the VFS inode are propagated to the inode in the page cache and are then written to disk, making the corruptions permanent. Moreover, if the superblock in the page cache is corrupted and flushed to disk, it might result in an unmountable filesystem"
Intel is more likely to support ECC in lower end CPUs (ex i3) than in mid to higher end CPUS (ex i5, i7)
i7-class Xeons (E3-XXXX) support ECC and are usually priced basically identically to their i7 cousins. i3's get used in tiny NAS systems like HP Microservers, probably why they come in ECC variants.
Another difficulty for a consumer oriented company like Apple, making using ECC not really an option for them
I'm sure Apple are more than capable of pushing for it if they considered it a priority. They have the purchasing power, they have the margins, they have the PR to make people wet themselves over the benefits if they so choose.