Knee pads - necessary?

I wondered the same thing when I started skiing, then I realized that I was constantly nursing bruised knees throughout the season just from skiing aggressively and having my knees make contact with the topsheets.  I don't know if they've ever saved me from a season ending encounter w/ a rock or stump, but this should attest to their confidence inspiring protection.  I bought the Arc'teryx pads and love them -very light and low profile.  I don't even notice them on the skin up, and they're more comfortable to carry on my knees than in my pack.  
I remember the first time I wore them.  Within a run or two I smacked my knee into the top of my ski  -my learned reaction was to cringe from the pain, but alas...no pain !  These things go into the "best money I've ever spent on ski equipment category (and I covet my ski gear :.)

-I didn't need 'em for the initial phase of learning lead changes and stuff.  In a weird way, I'm glad I learned why i needed them before I used 'em.
-I've gotten so used to them, I'm paranoid of forgetting them and skiing w/o.  -I fear I'll ski the way I do w/ 'em and take a patella beatdown.
-If the road down the mountain is treacherous, I leave 'em on to protect from the higher likelyhood of auguring in on the way home.
-never thought about the thermal protection when kneeling on snow, but its a no-brainer.

OK this is ridiculous, when's it gonna snow?

It's devastating to hit an object at speed with your unprotected knee. Therefore I always wear kneepads if I'm going to be making tele turns. Except yesterday - and I have a bloody knee to show for it.

Kneepads?  Always!  You can nail your most vulnerable and needed joint in any number of ways:  rocks, stumps, your ski  edge.  Last year, my friend Mary actually split her femur like kindling when cross-country skiing on a poorly covered logging road...knee landed on a sharp stone.  Freak accident, but it shows you what can happen. :'( :'( :'( Even a cheap pair from the hardware store is much better than nothing!
-Bill

I always wear kneepads. For years I thought they were unnecessary. Two years ago I hit a hidden stump in deep pow on opening day at Mission Ridge. I put a pretty good divot in my quadriceps tendon were it attaches to the patella. I could still ski that season, but had to deal with an ever growing, traumatic bursitis. This required multiple aspirations. I think I got away lucky. After starting to wear kneepads, I realized how comfortable they keep your knees throughout the day. Kneeling in snow, cold lift rides and other circumstances never mattered any more. I then realized that most of my ski friends wore knee pads, alpine or tele. I think it's smart and probably does more good than a helmet. YMMV.

I then realized that most of my ski friends wore knee pads, alpine or tele.

Really? I don't think I've ever seen any alpine or AT skiers with kneepads, at least outside of the park or "extreme skiing". With a fixed heel you're looking at impact injuries only after an ejection, and at that point you might as well as why not elbow pads, spine protectors, or any other body armor.

I think that the consensus vote is to use knee pads of some sort for tele.
I have friends that tele without them, but the risk is theirs.
Years ago I purchased a pair at a motocross shop that are ergonomic, thinner plastic shell with soft thin layer of neoprene/foam inside, held by a single Velcro strap, that fits right above my calf. The nice part is that they extend down just above the top of the boot (you can trim them to fit). Since they are thin plasitc, they are light weight, fit under spring softshell pants, and in case you egg beater your skis won't come around and slam you in the shins. That is a big plus, anyone who teles at any level knows the joy of a ski slammed to the shin bone on a beater fall.
I have thought of using these for alpine, but mostly lift skiing since the aggression level is higher and more prone to a good knee slam (like a fall in the icy parking lot)  .