There are at least two reason that I know of that it makes sense to use static over dynamic. First being that in many cases software based iscsi targets often listen on multiple IPs by default, if the sever is multi-homed. You don't want iscsi intiator to obtain IPs of a target for which intiator has no way of reaching.
Second being a situation when you have a iSCSI-based shared storage in an Active-Active configuration, allowing you to pin down certain hosts to certain storage nodes. That's when 'Static' comes in handy.
Cheers.
