ok i see where you have come from, taking the last example
(LE) 0xff981604 = (BE) 0x041698ff = (DEC) 68589823 68,589,823 is in hex 0x041698FF which is a close representation to a big endian ordered value anyway, so the only real meaning full values that you might load in $bigendian( ) is a string representing a Low Endian value in which case it would swap it around as per your specs, actually it might as well be called $endian( ) and the function would work in both directions, as 12345678 becomes 78563412 and 78563412 becomes 12345678.
Still would it be that usefull, not exactly a large number of people would ever need to convert a hex value to LE order or viseversa?
Still no reason not to have something is it

/me runs off yealling BigEdian BigEndian BigEndian
PS: i did think $reverse was a little silly tho!