Eagle Claw "failed", in the sense that it did not achieve its objective of rescuing the hostages from captivity, from one proximate cause:  bad weather (and its sequelae) that could not be overcome.

Some of the helicopters got lost (this was before GPS) and therefore delayed and/or damaged (to the point of being unusable) in the weather (a sandstorm), then there was an on-ground collision involving a C-130 and a helo, and a failure of reconaissance which vitiated surprise.  

The first two issues led to the force having insufficient helicopters to complete the mission.  The plan had a built-cushion of 2 helicopters:  8 flew but only 6 were needed.  After subtracting from the force the helos lost/damaged in weather and collision, there were only 5 flyable helicopters left.  The plan - and this was briefed in the WH - could not be carried out with only five helicopters.  Period.  Everyone knew it, everyone accepted it and, when it came down to five (even though there was discussion about going forward with five), the decision was made to stick to the plan.  

The weather also made for serious delays in carrying out the plan - the late-arriving helicopters (late because they got lost in the weather - this was a number of years before GPS was available) were not able to complete refueling and reach their preplanned "hide site" with enough darkness left to complete hiding them from prying eyes (and ears) prior to sunup.  They would have been discovered.

The last - failure of reconaissance - was due, in large part, to there being no effective on-ground human assets in Iran at the time:  no one knew what the bus schedules were in that part of the world and an overnight long-haul civilian bus (full of passengers) bumbled onto the refueling site right as (a) the refueling was going on and (b) the collision took place.  There was no way to hold them up (a whole busload of people going missing would have drawn attention at the next bus stop) nor to dispose of them (we don't do mass killings of civilians).  To make matters worse, more traffic started showing up after the bus.  Probably well over a hundred civilians....

Charlie Beckwith wrote about the mission and creating Delta Force, in an eponymous book.  It's a good read for a rainy afternoon.

The present situation is vastly different.  We have a ship, an unpowered lifeboat, 300 miles of ocean between the two of them and land, and nothing but time.  No one needs to surprise anyone, and all that really needs be done is wait.  The pirates know that if they harm their hostage they will die and have the hope that if they do not, they will live.  Rationality (I know - often in short supply) would dictate surrender.