Cheating on Victoria was part of the process, it needed to be told, so they could understand the full extent. Lily and Marshall breaking up was a huge event in their lives and something they all had to deal with. Same with Marshall's dad dying. If those events were huge events for Ted, and they were, why wouldn't he include them in his story?
If Tracy was still alive Ted would be happily in love. There is no reason to tell the kids that much information on his history with women, especially Robin who is in their lives still. The kids already know how their parents met, they have heard multiple stories. Wait For It episode.
hey are big moments for people and affect everyone around them. Ted and Marshall are so close, Marshall's father dying probably felt almost as bad to Ted, if only because of how bad Marshall was feeling.
But it makes more sense that Ted was telling the kids about Marshall and his Dad dying because the kids would have gone through the same pain, not just for the sake of telling a story.
As for Robin and Barney cheating, that's part of their love story and showed them getting back together. It was important to their story and while that fact may not be the best to include when telling his kids, he did it anyway. Ted's a perfectionist. And he also makes bad decisions, this was one of them. And this is just an argument in general, it has the same issues with either ending. If he was asking them for permission to be with Robin, why would he need to tell them about that anyway?
Because at that point the kids only know Robin as a family friend they have no idea how important Robin has been in Teds life. To tell the kids the crap that Robin goes through will help them understand Ted and Robins relationship.
He wanted them to understand the gravity (no pun intended) of the situation and how important it really was to him. The writers didn't need to add this part in, but they did, because they needed to. Because Ted needed to be done with her. He had to be done with her. Had they truly wanted him to end up with Robin, they should not have had this happen. Ted would still love Robin, and after the mother dies, would make sense for him to run back to her.
This of course would shit all over Tracy, but that's basically what they wanted to do anyway. My point is that they told the story the natural way, and naturally, Ted was over her completely, and the whole final scene completely ruined that development and felt weird, unnatural, and just downright bad writing.
The writers knew they didn't want Ted and Robin together at that point in time. Well we knew that Ted got married and had kids, it was never stated that they were end game We never heard Future Ted reference Tracy in his present timeline.
Just because you WANT to do something a certain way, doesn't mean it SHOULD be that way. The best example I can give here is George Lucas. If the original trilogy was the way he originally WANTED it, it would have been dreadful. That is why the prequels are so terrible, because he got his way for them. The original trilogy, before he had the power to demand things done a certain way, smarter people said no to stupid ideas because they didn't work. Maybe not but it was their story and they got to tell it. Some people loved it some people hated it. Guess it depends on your experience and POV.
he writers wanted Ted to be with Robin, but because of that scene and everything leading up to it, it was wrong. It no longer was the way the story was going and they forced it back in, which is the issue. As I said above, the writers wanted Ted and Robin just not when they were younger.
You should have been prepared for Ted and Robin endgame at least.