First, please  do  excuse my English, but  this technical stuff  sometimes is  
tough  to explain. I  think  wrapping legs  after a ride is  just one of  
these typical human behaviorisms of "pampering"  everything you got and 
maybe  not getting  enough in taking  care  of your  horse. As you  
statet  right, it does  not provide  the  significant support  as is  
often claimed. After rides (and once  again   I am not  only talking  
about Endurance, but  any  kind  of  tougher ride -dressage,  jumping, 3 
day   eventing-),  if  there  is   a  creek around, I prefer to lead  
them  in  there and  let  them  stand  in there. The  flowing  water  
provides  a wonderful  kind of  massage and cools  the legs. Sometimes  
you don't  have  any access to a creek, then  I prefer  to hose 
(spelling?) the  legs down.  And  if  there  is  no creek  and no  hose, 
my  last  joice will be wet  wraps (polo wraps, or "Bandagen").  On  
these  wet wraps I always  keep  a close  look,  because  they tend  to  
get  a little  stiff and  smaller  as  they dry off and I  don't  want  
to cut blood pressure  of. But  they  seem to take   any heat  out of  
the legs (nice cooling),  you can  always 're'wet   them...
Other than  that  I  use  leg wraps  on  uninjured  horses  only while  
trailering.
As  I  said wrapping  uninjured  horses is only one  way of pampering  
your horse. There  are  people  out  there who   seem to  have  a  
thousand  gadgets around  their   horse:  5  different  blankets  for  
five  different kinds of weather,  this  ointment for  this, something  
for  that,.....I   think  a horse  that  has  the opportunity  to  walk 
around after  a ride in  a  fenced  off  area around the  trailer or  
gets walked  a couple  of  times is  well  able to take  care of  itself.  
Katja  Laubin, Germany