My first disagreement is your comment on the writers have turned to sex to sell the episode. That was not the point of the episode. The point of Malcolm's part in the episode was a) to demonstrate that Malcolm is a teenager and, like it or not, teens are bound to try drinking at some point. Just because they aren't supposed to is the reason they do. b) to see how Malcolm's principles stood up to "real life." We see Malcolm fighting his principles in a few places throughout the ep. First, to ditch his family on Thanksgiving; second, he didn't originally want to take the beer; third, should he "take advantage of a drunk chick?" c) to build on Malcolm's social status for future episodes. Face it, in seasons 5 and 6, Malcolm is pretty much a loner. He doesn't hang out the Krelboynes, and doesn't seem to see Stevie too often either. He's just kind of settled into a state of depresiion. Maybe this episode is part of the reason: anytime he tries to make friends with anyone, he suffers. So why bother?
As "unappealing" as Malcolm's storyline was, it made up only half of the episode. The other half was "truer" MITM with an emphasis on comedy, rather than on the pains of growing up. You pointed out Reese's misfortune in the kitchen--perhaps the funniest part of the episode. Dewey's charade has been pointed out, but no one has pointed out Hal carrying out every wish of his son. Reese had total control over Hal, because Hal wanted the "perfect Thanksgiving dinner." He didn't trust Reese and the muckfish, but in the end it turned out brilliantly.
Or, ironically, it would have turned out brilliantly if Malcolm hadn't puked in it. Malcolm puking in the turkey wasn't the funny part of the scene. To see the humor, you had to dig deeper and realize that Hal, who had obeyed Reese's every command for the turkey, was now unable to enjoy it.
Finally, J, were you any good as Scrooge? A useless tidbit of information: Frankie's first bit of acting was as Tiny Tim in A Christmas Carol when he was 8 years old. Maybe J is the next big thing!