Remain truer to what, he wasn't exactly fleshed out in any meaningful way in TOS. The most general audiences remember is that he's the one who talks funny. I've got a cast of seven main characters, two antagonists and a new science officer that I have to work into the story and I have two hours to do it. Under those storytelling constraints, I have no issue with Chekov being handed the chief engineer duties. In the real world I still don't have an issue because of familiarity. I hate to say I did exactly what we're discussing here because I promoted a lesser qualified candidate because I had worked with the lesser qualified candidate and was comfortable that person could handle the job better than the more qualified candidate. It's never as black and white as you'd like to make it sound.