I have asked this question before as well..
The "status change" events have underlying statuses that affect the severity - so for example the PFAs show up as minor. The only way I have been able to work around this is to set up a new event collection for storage-related conditions and include Warning and Minor and have the event handler send a ticket (we use HPOM to talk to Remedy). This way, we don't miss PFAs.
The only other way i can think of is to modify the SNMP MIB, however from my understanding, you can set them ALL to be a single severity, so that means status changes of "OK" will also trigger a critical event, from previous discussions I had with HP on this topic.
The RAID battery condition is similar - it uses the status change type of trap.