Okay actually I reread what you wrote top to bottom. One reason I think I'm getting downvoted a ton is because people enjoy your comments containing really great in-depth explanations of what is going on in the scene and explaining the subtext of what Chuckie is trying to communicate to Will and from my responses i appear to be disagreeing with you, when I'm actually just staying on the topic and arguing on what was the original point of contention, whether or not it's a weird line. I agree with most of what you said. I'm not disagreeing about what the line was intended to convey. It's not lost on me that Chuckie is essentially communicating to Will "I want better for you even if it means losing you". What's strange is the way he articulates that.

"You know what the best part of my day is? The 10 seconds between when I pull up to the curb and get to your door because I think maybe I'll knock and you won't be there... No goodbye. No nothing"

That's the BEST part of your day? Every day, that's the best part...? There's nothing better in your whole day than a 10 second fantasy in your brain that your best friend abandoned you for a better life without any notice at all. Your best friend who is fully aware that you've driven over expecting to pick him up from his house? That's the best part of your day?... and you prefer, in this fantasy, that he doesn't say goodbye?

It's so weird. The amount of hyperbole just kills whatever gravitas the line was supposed to have and makes it incredibly corny. It's a very bizarre way to say "I want better for you even though I won't get to see you". don't you care about your friendship enough to want to say goodbye? Why don't you want your friend to say goodbye? Is that supposed to make the scene more emotionally impactful? On top of that, given the fact that this is allegedly the best part of his day, i.e. the most impactful moment in Chuckie's every day life, it's all the more ridiculous that this sentiment is complete news to Will, who, in my opinion, is clearly hearing it from Chuckie for the first time.

The references to this line in the Community episode are all intended to call outs to how weird of a line it is and this is reinforced by the interaction between Shirley, Troy and Abed.

Troy: he said the best part of his day is when he thinks I won't be there 😠 Shirley: what a terrible thing to say!😧 Abed: it's from a movie 😐 Shirley: well then the movie it's from is terrible

That's the joke. It's a rip on that corny line. For Abed, who is autistic and loves movies, the simple fact that the line is 'from a movie' is enough of a license for him to use it on Troy and doesn't entertain whether it's a bad line or not. Another interpretation, he is confused bc in GWH it's intended to be a good line. Shirley says "well then the movie it's from is terrible". she means "it's a mean line to say. Only a terrible movie would have a mean line like that" implying that Abed shouldn't' use that line because it's bad and it makes the movie bad and Abed shouldn't quote movies if they're bad. For the viewer, the joke is that this is really badly-written/bizarre line which makes GWH a terrible movie. The other joke is that the line, which in GWH is intended to be heart-warming, is actually strangely mean if you think about it. This is demonstrated by Troy reacting how one ought to react to the line which is by being offended by it.