"There music is much of a muchness with that of their contemporaries."
That's pretty much it. They're a bland, safe mainstream take on that sort of music.
I remember when Coldplay hit it big and were being hyped up by the alleged critics. First time I heard "Yellow", I was like "This is what all the fuss is about?!"
This- along with the hype for Damien Rice's bathetic "Cannonball"- was what finally stopped me caring about what the mainstream media deemed The Next Big Thing.
Someone put their finger on Coldplay- at least in their early days- when they described them as an A&R man's version of Radiohead using "High and Dry" (#) as the basis for their career. (And- one assumes- not going on to record "difficult" albums like Kid A instead).
Of course, they've moved on with musical trends since then, jumping on with a conservative take on what will keep them popular (e.g. increased number of collaboration/featuring tracks in recents years as has become common in chart music).
A safe, commercially-friendly take on musical trends. The "Next" of rock bands.
(#) One of the most commercial, but also weakest songs from "The Bends"- even they don't like it, apparently.