Yeah we got sidetracked trying to define comedy
Although this is a simplification of what you said, glancing at it you said the kids were a plot device and it shouldn't be taken seriously that future Ted is actually telling them all these stories. And that the mother is also just a plot device and isn't the 'point' of HIMYM.
Rather than arguing as such. Let me just outline my general complaints about the 2 issues.
HIMYM's first season was really strong. The story was clear and focused. Very much as you described it showing Ted as the hopeless romantic who just had to see where things would go with Robin even though signs pointed to disaster.
I could see a show existing like that. If each season had had a similar focus and felt like it really was a journey Ted was on then I would be happy to only meet the mother at the very end.
But that focus was gone once the 2nd season began. The creators have been making it up as they went along for a long time. Which would be fine if they'd made up good stories but I don't think they have. I've not been satisfied by any of Ted's other relationships or his backsliding with Robin or the flip flopping between loving and hating the single life. So to keep teasing us about the Mother has become an irritating part of the show. It's a reminder that the show once had a clear focus where meeting Robin would lead to meeting the mother.
But eight seasons later I'm not saying anything shocking by pointing out that they've stretched that premise to the point where it no longer feels believable. The more they tease that it will be coming soon the more preposterous it is that he's actually been telling his children this story. Of course I don't really believe that he sat down and told his kids hundreds of hours of story. But the show insists that he is telling them a lot and the more they mention it the sillier it seems.
For me that silliness affects my enjoyment of the show because it keeps breaking my suspension of disbelief. If it doesn't bother you that's great. But it's hard to argue that they are meaningless plot devices when the writers use them repeatedly and build their emotional resonance around them. e.g. the great ending of episode 20 this season which I praised a lot.
p.s. Here's a bunch of comedies I've really liked at one time or another: Fresh Prince of Bel Air, Friends, Frasier, Seinfeld, Simpsons, Family Guy, Scrubs, Spin City, Cybil, The Office, Louie. And UK shows Black Adder, Red Dwarf, Men Behaving Badly, Bottom, Coupling and a whole bunch from pre 1980