I guess I might contribute a gameplay-related issue to the list, despite the subject line.
* More minigames with more depth
It's become clear that the puzzles in an episodic release simply can't have the same depth as a single full-length game, so it makes sense to augment the gameplay experience with some form of skill-based minigame, which would also have the added bonus of increasing replayability (and therefore "value") - something that's been lacking from adventure games of any duration.
As far as adding more depth to the minigames, that's a trickier subject. Of course, everyone here should remember Carbomb from Hit the Road.) I was disappointed that driving around aimlessly in the first episode didn't have some sort of minigame aspect to it.
These wouldn't even necessarily have to be integrated into the story, but usually these sorts of things are done in a way that you have to at least get a minimum score to progress with the story, but you can go back and play for fun if you want.
Suggestions that I could make would be things like some form of Hangman with Sam-and-Max related words, a shooting gallery (like the HtR end credits), a diving minigame on the street where you might have to jump over, drive around, or shoot certain obstacles, any sort of old-school arcade game on Bluster Blaster would be a shoe-in, and I'm trying to think of a way a DDR-style response game would work, but can't really come up with anything right now.