That would have COMPLETELY changed the tone and story of the film, since Harry Mudd is a comedic villain and a slimy con artist instead of the "cold-blooded, revenge-seeking madman" angle they wanted for their "darkness" promos.
It also would have shown that JJ Abrams & Co. actually "got" a major aspect of Star Trek, since Harry Mudd is an actual example of the "Joker" to Kirk's "Batman", as a reoccurring villain who is a major arch-enemy and constant thorn in his side. Khan was only intended for a single episode and didn't get his iconic status until he was reused in Wrath of Khan, and THAT worked because he was a bitter, changed man AFTER being stranded for 15 years. Take away THAT element (which they did in Into Darkness) and he's just another forgettable strongman foe from the original series.
Furthermore, Cumberbatch was nothing like the Khan from the TV episode "Space Seed", personality wise. THAT Khan was a charming, arrogant, seductive guy. I actually thought these guys would respect the source material enough to use a villain from the original series that fit the kind of story they were telling (instead, they did the opposite -- came up with the story first and forced Khan in there when he didn't fit). Based on the trailers, it looked like they were using Captain Garth from the third season episode "Whom Gods Destroy", which would have been particularly clever since most people aren't familiar with him, and there was tons of possibilities they could explore to do something new with him, since the original episode was confided to a mental asylum on a planet where he had escaped and was holding Kirk captive. From the episode, we learned that Garth was:
- A rogue, out-of-control Starfleet officer
- Highly decorated and better than Kirk "at everything"
- Gained the ability to shape-shift and change his appearance from alien race
- Driven insane and hell bent on committing genocide
- Masterful tactician dedicated to getting revenge on the Federation
In short, the character fit perfectly for the kind of story they wanted to tell, and there was tons of stuff they could have done if they set it in the "2259" time period and gave us a scenario like Garth escaped custody and never made to the asylum. Alas, we got Khan In Name Only instead.
Bleh. You’re trying to think coherently. With Abrams, it’s all StarWarsfanboi revisionism, defecation and lensflare.