(Probably. I mean, I have a lot of feelings on this, so who knows, but I'll try my best.)
I've been reading a lot of responses to the finale, and maybe engaged in one debate with a person I don't know on Facebook (yes, I hate myself for it. No, I can't stop.) and the thing that drives me crazy is that any defense of the finale doesn't seem to understand what the actual problem with it was. I've heard people say that this is the more realistic love story, because sometimes people die and then you move on and you don't just have one love of your life. And I totally agree. I *love* realistic love stories. But to me, Tracy and Ted were the realistic love story. There was really nothing epic about it - they met through acquaintances and circumstances, and hit it off, and built a life together, and sometimes fought or had ups and downs, but worked through them. The only thing "epic" about it was in Ted's head - his description of Tracy and how they met is the only really exciting thing about them, which is true to life of most couples! It's his relationship with Robin that's ridiculous and over the top, and on-and-off-and-on-again and filled with grand romantic gestures over compatibility and working to build an ordinary everyday life together.
I'm also totally fine with doing a story about losing the love of your life and grieving and moving on and finding that you can have multiple loves of your life. It was beautifully done this very season with the mother's story of losing her boyfriend and finding Ted! You can argue that it was foreshadowing, but to me, it just made the ending even worse, because we had this beautiful example of what they were going for, actually done in a way that made sense for the characters, and the finale was so not that.
Which brings me to my biggest issue with the Robin-Ted ending: Robin doesn't love Ted. A lot of people are saying, "it's perfect, they couldn't be together before because they had different goals in life and now they've reached those goals and can be together," but that's totally missing the point of why they weren't together all this time. Every time over the past few seasons, the thing that's driven Ted and Robin apart hasn't been the kids issue, it's been the "Robin doesn't love Ted the way that he loves her." When they called off their "let's get together if we haven't found anybody" pact, the conversation isn't about incompatible goals, it's about the fact that it's killing Ted to be so in love with Robin and know she'll never feel the same way. When she's freaking out over her wedding with Barney, she thinks maybe she should be with Ted because he's always there for her and loves her so much, and he doesn't say "no, we can't be together, because you don't want kids." He says, "no, you don't love me." Even if things didn't work out between Robin and Barney, it doesn't change the fact that Robin loved Barney in a way she could not love Ted. And the show did nothing to show us that her feelings for Ted had changed and she suddenly could be interested in him romantically, it just tore her down so she would be desperate and lonely enough to be happy when he came knocking on her door.
Fuck that shit. This finale was so disrespectful to characters that viewers had come to know and love, and that's why everyone's mad. Not because it was a twist or because it wasn't the ending we wanted.
ETA: one last thing! This ending would have also worked a lot better if I hadn't spent literally every single scene this season where Ted was trying to get over Robin going "oh my god, I get it. Ted needs to move on because he and Robin are a TERRIBLE couple and she's NOT INTERESTED. Can we get back to the charming/adorable/wonderful mother now?"