I agree with what Flyingdebris said about in game. Also depending on the status of my mech, your mech and out loadouts I have found the occasional time to leg even a green mech.
I do not remember what mech I was using, Adder or Kit Fox vs Deity in a Mad Dog. I had already been through a slug fest and was not in horrible shape, but I knew I could not take out a Mad Dog, so i aimed low and poped his knee. Now Deity did not like that... He vowed to remember the event, as have I as I found it in good fun. I have had my leg blown off, sure it sucks, but then you get to try and pop off as many shots before the other mech comes to smush you into the dirt. Hell ONE time in maybe August I got legged and then legged the guy who legged me as he approached. Was good fun!
As for the whole honor aspect. I have been one to toss into the in game chat fire about the clans not having much issue in legging as it allows the mech to be salvaged, less waste and as someone stated allows the loss of life... which is one aspect the Clans are VERY good at... See that bad control panel? Well it still has some LEDs and circuitry, let us take it apart and use the LEDs for replacement parts and the circuitry has uses elsewhere.
This is not to say the Clanners go around taking cheap shots and ONLY legging... that is wrong... But the occasional tactically sound legging, sure.
Now from Way of the Clans novel...
A BEAUTIFUL HURTING MACHINE."
"If you think kill, you will kill."
"IF WE THINK KILL, WE WILL KILL."
"If you have a boot, you crush your enemy."
"IF WE HAVE A BOOT, WE CRUSH OUR ENEMY."
"If you have a hand, you strangle your enemy."
"IF WE HAVE A HAND, WE STRANGLE OUR ENEMY."
"If you have a club, you bludgeon your attacker."
"IF WE HAVE A CLUB, WE BLUDGEON THE ATTACKER."
"If you have a knife, you stab your foe."
"IF WE HAVE A KNIFE, WE STAB OUR FOE."
"If you have a gun, you shoot it."
"IF WE HAVE A GUN, WE SHOOT IT."
"If you have a tank, you roll it over the opposing ranks"
"IF WE HAVE A TANK, WE ROLL IT OVER THE OPPOSING RANKS."
"If you have an aerofighter, you bomb them."
"IF WE HAVE AN AEROFIGHTER, WE BOMB THEM."
"If you have a 'Mech, you win."
"IF WE HAVE A 'MECH, WE WIN."
"You are always the victor."
"WE ARE ALWAYS THE VICTOR."
"When the blood is spilled, the bloodname is earned."
"WHEN THE BLOOD IS SPILLED, THE BLOOD-NAME IS EARNED."
"We are the Clan."
"WE ARE THE CLAN."