Of Monsters and Men disappointed me with their second album.
As mentioned by another user, Mumford & Sons went a weird and unfortunate direction.
I’ll say that I am glad that The Postal Service dropped one perfect album and never released anything ever again.
Also, while Daft Punk did change over time (maybe hardcore house fans grew to hate them), I would argue that their albums only got better over time and their final album was absolute musical perfection.
Their breaking up was the most bittersweet decision I’ve seen in music.