Why ZFS's data integrity is less important than Solaris's usability
The bottom line is that Solaris is hard to administer (yeah, it's a fair cop), so server data is just going to have to suffer. Hopefully some day Solaris will be as easy as redhat, or debian, or ubuntu, or <insert name of distro here>. Some day. Meanwhile, I'll choose data integrity over ease of administration.
The problem with this is that quiet disk corruption is not currently a big issue for most people; it just don't happen all that often, at least that people notice, or people would be howling in pain right now. You can argue that people just haven't noticed the corruption that they're experiencing now, but the counter-argument is that if people haven't noticed it it's clearly not that important to them (yet, more or less).
Or to put it another way: the problem for Sun is that they are trying to sell a better mousetrap when people don't feel that they have a mouse problem (or at least not a mouse problem that their existing mousetraps can't deal with).
(Perhaps Sun has done studies that show that disk systems and so on are going wrong much more often than people expect, or that future disk systems will inevitably have higher error rates, or the like. That would be newsworthy and I would expect to find that sort of stuff mentioned at the ZFS pages.)
Even without a mouse problem, people would still go for the better mousetrap if it was otherwise a more or less neutral choice, but it is not. To extend the metaphor, the better Sun mousetrap is uncomfortable and has sharp bits that poke you reasonably frequently. That it is cool and nifty starts to fade after the first few times you have to apply bandaids.
And that is why ZFS's data integrity features are less important than Solaris's ease of administration. In practice, ease of administrations matters more to more people, because right now relatively few people are seriously worried about silent data corruption whereas everyone has to administer their machines.
(In other words, people will indeed often choose practical ease of administration over (theoretical) data integrity, whether or not they are willing to admit it out loud.)