Yes, perhaps it’s just less acceptable in more ‘formal’ styles of writing.It's all about context;...
“AAAaaaaaarrrrrrrrrrrrrrrrrrrrrrrrhhhhhhhhhh!’
Or,
He let out a long slow agonising sigh.
The former, to me, sounds like something I would read in a Batman comic (not that I would read one of course --much). On the other hand, when did you ever read about a superhero ‘'letting out a long slow agonising sigh’?
I think the problem I have with these 'oooohhs', and 'aarrgghs', is to me they feel kind of light --a little like the old 'showing rather than telling'. Or, can a good author use and manipulate them be as exciting to read as when they are heard?
As for *lol*, well I guess it’s just ‘chat’ jargon, on line it’s often just so easy to be misunderstood. The other day, I was chatting with a dom about titles such as Sir and Master. He said, and I agreed, it wouldn’t matter what people called him, he’s still the same person. So, feeling silly, I called him a ‘fat ugly bastard’. He wasn’t amused. I guess I should have added lots of *lol*.
Alex.