Bilbo was hired to be a thief. Not a marksman, not a cook, not a light-hearted and jaunty companion. A thief. Mold: cast.
Merry and Pippin were self-centered, self-absorbed whiners who were worried only about from where and when their next meal might come. I don't give a damn about how their characters matured throughout the stories; first impressions literally made reading Fellowship the most unremarkable experience in my reading career, and I will say with all honesty that I haven't finished it, not will I ever attempt to read it again. These images and behaviors have saturated the Halfling, and everyone I've ever known to play a Halfling plays them this way. I aggree that the Halfing (and its various offshoots) have a stigma attached to them, but its a self-fulfilling stigma, and I must strongly disagree with the statement that a Player will play any PC in this way. Never have I seen someone go from playing a coniving, thieving, greasy-mouthed Halfling to a coniving, thieving, greasy-mouthed Dwarf.
I played a Halfling many, many years ago (definitely not my first choice of character) in a local Con event, and the GM took me aside afterward and told me he was astounded with my RP of the pregen character. I was a Fighter/Thief, I was the stalwart leader of the party, I took risks to save lives, solved riddles, and was quite heroic. I never sat there thinking "I'll backstab it" or "I sure could use a muffin about now" during the entire combat encounter. I didn't cook anybody's food, I didn't steal from other party members (or anyone else, for that matter), and I didn't run off looking for loot on my own. Maybe it's because I hated them so much that I was determined to make them different, break the mold.
And of course, those who hate Halflings hate them because of previous RP experiences. It's not because we're racist; we haven't met any in real life that have rubbed us the wrong way, stolen our stuff, made us sit around wondering where the eff they are, and generally sowing tension and mistrust everywhere we go.
Back in the day, WFB Empire halflings used short bows, and huge slingshots to lob large kettles full of boiling stew at the enemy. And they fought side-by-side with big, dumb, brutish Ogres. The models were sculpted as tubby-gutted midgets with cooked chicken legs hanging from their belts. Mold: used.
"Hi! I'm a Kender! We're awesome, 'cause we like maps and misappropriating other people's stuff! Gotta go now! Wanderlust gives me the attention span of a goldfish! Oooh, look! A dragon! Ima say hi…" So annoying. Maybe (and I say maybe) they were good for a laugh in the novels, or being a broken-hearted crybaby for the human nature of a tragic plot device, but not so much in RP. But, new-old mold: cast.
Dennis McKiernan (author of 'The Iron Tower' trilogy, 'Eye of the Hunter', 'Dragondoom', etc) hated Halflings (and their kind) so much that he envisioned an entirely new race of humanoid to replace them; Warrows. Essentially, they were smaller versions of elves, but with distinct differences and traits. They weren't thieves. They weren't chow time cooks. Some were good with bows or slings, others with small swords. They stood toe-to-toe with Rock Trolls without bawling for someone to save their ases. They were honest, hard-working, heroic, staunch and loyal, intelligent, and gregarious, not social misanthropes.
In 'Band of Brothers', Malarkey did a lot of the cooking, he was a friendly guy, talkative, joking, good with a rifle. He wasn't annoying, running off on his own, constantly chomping on some bit of food-cud, or stealing from his buddies. Malarkey was a Ratling. So, like I said, if someone wants to play a Ratling in an OW game I run, it'll be a Human referred to as a Ratling. Ratling will be a Specialist "slang" word with prestigeous conotations. Not a disparaging term for a short, rotund, nappy-footed, deadeye shot who's a compulsive eater/pickpocket.