Literally loling takes extra effort to type and conveys to others that lol is not just being used as a sentence-filler by someone lazy or pretending to be amused and therefore should be used sparingly for those true lol moments.
Furthermore, it's use can expand past type/text scenarios when describing a literal lol moment.
Metxt: OMG! At TAO, I was dance raped by a Puerto Rican midget chic from New York while her husband was snappin photos saying, "What happens in Vegas baby!" True story!
K-rizztxt: Woah dude! I'm literally loling! I wanna see the pics!
later that day (in a non-textversation)...
Kristi: Dude, you can't send messages like that while I'm at work! I was literally loling and was asked "whats so funny" by my obnoxious cubemate.
Me: Who cares check out the pix on my facespace!!! It was such a the hangover kind of weekend!
Kristi: Sounds like it, if you didn't have proof I'd think you'd pirated it from TFLN.