Lennart's opinion about "valid" daemon's behavior is very, very wrong. And this is not opinion from more-or-less anonymous reader - this is opinion systemd creator and developer. Sorry, I don't see any pros from (for example) MySQL that creates missing databases itself. But I see drawbacks thats may lead to subtle and annoying situations.
Yes, of course, with simple installation, on single machine, witch typical scenarios it's doesn't matter - is databases created from script or by daemon. But uni*xes strength comes from diversity and - again - flexibility. Users and operators probably never deals with non-standard installs, but admins - yes.
Lennart's rants about separate /usr or /var ("Go to Slackware 1.0 then"), surprises with DoS via /run/user (and their "workaround", blah: http://lists.freedesktop.org/archives/systemd-devel/2011-...) clearly shows me that he isn't a sysadmin and don't care about different needs. But he has vision. This isn't enough for reliability and flexibility.
PS. that wasn't fictional case, I took it from official mailing-list.