The behavior you noticed is due to what I consider a highly
questionable change in the semantics of symlinks.  This change was
inherited from 4.4BSD-Lite.

Basically, a symlink is considered to have no attributes of its own,
other than the type, size (which some programs use to allocate buffers
for readlink(2)), and link count (which should always be 1).

What this really means is that the permissions and time stamps are
considered to be the same as those of the directory containing the
symlink.

There are some disadvantages of this behavior:

1) There's no way to see when a symlink was created.

2) The problem you mentioned; it's impossible to remove a symlink from
a sticky directory that you don't own.

3) Having the inode number appear to be the same can be very
confusing.  (I spent a total of about 3 hours tracking down what I
*thought* was a bug in cd9660 causing this!)

Needless to say, I'm considering reverting to the previous behavior.

[Note: I don't read this list.]