Keep in mind that both Imagine Dragons and Sting/Shaggy are touring. They're not picking these artists out of a hat; they're promoting their new material and/or the upcoming concerts. Their bands, sound techs, lighting, etc., are in "tour mode" now, so they're good to go.
Imagine Dragons makes 100% sense, IMO. They're from Vegas. They're on the radio and car commercials. They have a new album out this past year. They're a fairly middle-of-the-road, inoffensive band. Yeah, they're sort of a mayonnaise sandwich, but not everyone is going to like the latest EDM artist.
Sting's more for the older set - i.e. pre-millenial. I'm a proud child of the 80s, so I'll confess my bias. But just scanning the Wikipedia discographies, The Police have 8 singles that are fairly well-known - I mean, "Roxanne", "Every Little Thing She Does Is Magic", and "Every Breath You Take" are part of the musical zeitgeist of people my age. With Sting a solo artist, there's also a few singles - "If You Love Somebody Set Them Free" and "Fields of Gold".
I honestly don't know any Shaggy songs other than his two hits in the early aughts - "It Wasn't Me" and "Angel". But he clearly comes with the Sting package.
No, they're not all my cup of tea, either, but I don't think the entertainment planning has been a tire fire. You can argue about whether you personally like them or not, or about the execution - frankly, I didn't pay that much attention to any of the performances. But these aren't "total gong show" artists. It's not like they dredged up Dishwalla. From a Boston point of view, both Imagine Dragons and Sting/Shaggy have been playing in some decent sized venues here lately - ID played TD Garden in 2015 and 2017, and Sting appeared with Paul Simon at the Garden, as well as doing a sold out solo show at the House of Blues last summer, and will be with Shaggy this summer.
