Coldplay, as a band, have 209 nominations and 62 award wins in several worldwide categories, from best international band to best live act and best video. They have over 80 million album sales, making them one of the top 100 best selling artists of all times. Your perception of hate is consequence of bandwagon effect which has been documented in other instances.
The psychological reason as to why people “hate” Coldplay, and basically all things popular, is a sum of several factors which I’ll try to explain:
1. When something is popular, there is no way to avoid being exposed to it.
The fact that bands like Coldplay are widely popular also increases the odds that people who do not like their music will be exposed to it, and since they are so popular there is no way to avoid them, leading to an overexposure to a concept some users already dislike.
2. Hating something is a social act
We humans, are social beings at out core, socialization is engrained in our DNA since it favors the perpetuation of our species. Hating something, is like sharing a hobby or an ideology, it’s a flag that unites human beings under a simple message and gives them the possibility to socialize. It’s like having a sports team: “Oh, you like red team? I like red team too. Fuck blue team.”
3. Popular things, by definition, need to be bland
Being popular means appealing to a very wide audience, and therefore has to be bland. Think of vanilla flavor, which is a basic flavor most humans can tolerate, but also is nothing special. The more “special” or segmented you become, the less wide your audience becomes.
4. Status Quo is safe
Coldplay doesn’t have a rabid fanbase correcting everyone on the Internet and defending the band, everyone knows they are the status quo of the current entertainment industry, not risking enough to try to be edgy and therefore require very little effort to find a song you like. They do not polarize audiences, they do not go to extremes and they tend to stay within very safe bounds within the context of whatever trend is going on that year. A band that size rarely takes risks outside their comfort zone, nor they have a good reason to do so. The only ones participating in the conversation are people who hate the band, since the rest of the audience just doesn’t really care enough to balance or polarize it.
Think of Kanye, which also has a multitude of haters, but an entire army that will defend and back his ideas because he IS a polarizing artist. Overall, the idea is that people “hate” Coldplay because the amount of exposure they have and because hating stuff is easy. It’s similar to the Nickelback trend.