We don't need melting icicles. Hoth is -3,000,000*C. Why would ice melt in the Wampa's lair? Unless the Wampa lit a match, there should be no melting ice. If we have melting icicles in the Wampa's lair, them Echo Base should be melted from all the heat from the machines and wires/cables.

We don't need to see icicles melting but It would make the cave feel like a real cave and animated and not just a movie set.

It's warmer inside the Cave than outside, theres a wampa living in it..Luke is also in it. There are icicles all over the ceiling... Icicles are formed by moisture collecting and freezing while running with gravity to earth. The Wampa has been actively doing something to fasten Luke to the ceiling generating heat in the area.

Assuming the Wampa is similar in biology to the Taun Taun they would be hot blooded and be mammalian in nature. The wampa would also need to urinate and breathe this hot steamy urination and breath inside the cave would help explain all the icicles as presumably the wampa eats snow as a form of hydration also.

Not sure on the technique the wampa uses but perhaps saliva to fasten luke to the ceiling. I will assume the process is done to have Lukes Blood collect in his head and upper torso and this is tastier and more satisfying for the wampa to eat. It would also be the hottest part of the human body tipping somone upside down would make your head even warmer...

but only a subtle effect of iceicles melting if any was added. and it's also meant to be a subtle device so your missing the point a bit there.

As far as echo base is concerned that actually does not make any sense but It's a fun movie same goes for the cave.