Yes, but Scotty wasn't defined by books, or short stories, or even so much by scripts. Scotty was defined, almost entirely, by how he was portrayed by Doohan.
If Doohan's performance is irrelevant, why not cast Jackie Chan in the role? Or Cheryl Crow? Or Paul Reubens? Or Rosie O'Donnell? I mean... if you don't care how the character was portrayed, presented, acted... all of that... in the past, what DO you care about?
Pegg is a fine actor with a much better range than most folks would attribute to him over here... but he's totally different from Doohan, and Doohan's performance is the ONLY thing that has ever defined "Scotty" in the past. So, the character he's playing is unlikely to have much in common with the character we've all known for 40+ years.
I'll wait until I see that performance. Until then we got nothing. Again Doohan's "Scotty" was a performance. He put on an accent and pretended to love his bairns and his scotch. All we know about Pegg's take is that his "Scotty" finds the Enterprise exciting and he has an Scots accent ( something that Doohan's version lacked according to some

) I assume the drinking will be established later. So we seem to be 2 for 3 right now.
Doohan's performance is not whats being discussed or dismissed as irrelevent. What is being discussed is how much an actor in the role of "Scotty" needs to look like Doohan or if his take should just be a bad immitation of Doohans's "Scotty". I've seen Doohan, he wasn't 100% "Scotty" in real life.
Far too many fans want the new actors to look like the previous cast and do impersonations out of an SNL skit.
That's not remotely what I'm saying.
Doohan's Montgomery Scott was a scowling, dour character with a real curmudgeonly "bite" to him. My mental image of Scotty is him, sitting in the captain's chair, eyes squinted as he stares down a hostile situation while Kirk and Co are stranded on a planet surface... or him growling under his breath as he crawls up the Jeffries tube to try and perform some miracle.
It's not the accent... or even so much the physical appearance... but rather the general FEEL. Scotty had his humor, sure, but he was often one of the more grim characters on the ship, and it just felt NATURAL to him.
Pegg can play "hard-ass" (see "Hot Fuzz") and I'd hope that his Scotty might incorporate SOME of that... but he's just so easy-going in everything I've ever seen him in. He lacks the INTENSITY that Doohan's version had, in other words.
I'm a fan of "Sean of the Dead" and "Hot Fuzz" and "Spaced" and most other places I've seen him. I just can't process him as being the same guy as Doohan was playing.
Maybe I'll be proven wrong. Maybe he'll be the most inspired bit of casting on the film.
Or maybe it'll be what I've been worried about all along... he's someone who Abrams already knew and liked, and Abrams gave this part out to have yet another of his pals around. Sort of "nepotism" without the blood connection, in other words. (Not that there's anything especially rare about nepotism where Star Trek is concerned).