Evil?
That's a word that implies morality, which doesn't really play into this.
Hated?
That's a lot easier.
EA aren't hated 'cause they're evil, the anti-christ, satan incarnate, the one who will bring about the apocalypse and who strives to do immoral things. They're hated because they are anti-consumer in many of their practices, and downright stupid to the extent that it hurts their consumers in others.
Lets run through a few of their known blunders shall we?
Ruining franchises. Whether the devs say it was them or not, there is a fairly clear trend that upon joining EA, many great development teams begin making rather shit games. Afterwards, the studios are shut down and the great games people loved from them are never heard from again. Amazingly often, this seems to be in order to try to appeal to a more 'casual' CoD styled market. No matter what the game is. Whether you agree with them or not, a large part of the community and fans of these SERIES will agree that the quality of the games went down the shitter in their latter installments; Dragon Age [2 was poorly received by fans of Origins], Mass Effect [3 was poorly received by a LOT of people], Command and Conquer [Pretty sure it was the latter Tyberium Saga games or whathaveyou that were poorly received], Sim City [The most recent one was an absolute flop]. There are also plenty that whilst they haven't had a majorly offensive [To the fans] game yet, are losing their tract with their original audience due to the direction EA is taking them - Battlefield [Always been a big fan of the Battlefield series. Haven't touched 4, according to friends who are like me, despite having Commander Mode back its more CoD than BF3 was, and that's saying something], KotOR [Whilst there are many that don't mind it, and those who actually thought it was decent before it went F2P, most will agree that SW:TOR was not what they wanted out of KotOR 3], The Sims [Almost everyone I talk to who plays the Sims prefers 2 over 3. 3 lost me, and several of my friends, however its still regarded as a decent game by some, rather than utterly horrible], Dead Space [3 was widely criticised for basically ruining the horror and introducing microtransactions. There are also many that disagree with this]. Basically, anything EA touches slowly turns to crap. Great Studios like Westwood, Origin Studios, Bullfrog and tens of others have been bought, ruined, and shut down by EA, and people are expecting the same of studios like Bioware and Maxis at this point, as a result of their recent releases.
DRM. EA is possibly the worst DRM user outside Ubisoft. Maybe even worse, IDK. Always online DRM, grasping onto Securom for as long as they could, at times limited number of installs for games - they don't have the best record for being non-DRM, and the DRM NEVER freaking worked. It would always fuck up in some way or another, destroying the experience of paying customers, and encouraging people to pirate simply to avoid said DRM, which causes more DRM to be put on in a failed attempt to stop the pirates, making the experience even worse for the paying customer. Despite evidence that would point to removing DRM getting you more sales [Yes, probably also more pirated copies as well, but if you're getting more sales its still a plus], they cling onto the anti-consumer practice until they realise they've not only shot themselves in the foot, but also the leg and have the gun to their heart about to pull the trigger. Only when a game is midway through dying will they remove the DRM from it, to try and say "Yeah, we listen, please come play again so we can sell you DLC". Obviously, that doesn't work.
DLC. Second only to Capcom... Ok, they aren't that bad, but they're bad. Mass Effect. At launch of Mass Effect 2 I count no fewer than 5 DLC packs available as a part of "Project $10" or W/E it was called. Mass Effect 3 launch, Prothean DLC that many count as critical to the plot, even though IMO its not, was sold as a continuation of the same incentive. Online passes. Whilst this doesn't personally affect me, many console players take issue with it as it means they can't get the full experience out of a second hand game. It also runs into the usual problems of DRM not working, locking new-game purchasing customers out of content they are entitled to by purchase because EA is incompetent. The prices on their post-release DLC are also quite high, but I don't care as I don't buy that stuff anymore. If the cost is stupid then I'm not touching it.
Terrible Customer Relations. When there was outrage over the ME3 ending, what was EAs reaction? "You just don't get it", "Artistic Integrity", and a bunch of other bullshit generally focused around insulting those who didn't like the ending, rather than at least being polite about saying they get what they got. Some good management of the situation here would have gone a long way. Instead, we get videos like these; https://www.youtube.com/watch?v=p5Oh76SiHzs popping up, and retaliation insults against the development team, which escalated the whole issue beyond what it needed to be. Eventually, after a good 3-6 months of pushing, we got an 'Extended Cut' DLC announced, and finally released. EAs advertising has constantly been off-base and tasteless as well, such as the "You're mum won't like it" Dead Space 2 advertising campaign. They often make it abundantly clear that they don't care what their consumers think, only their shareholders, and its one of the things people hate about them.
Of course, this does seem to be changing with the new CEO. Its looked like it'd change before and it hasn't, so I'm taking it all with a grain of salt, but ATM EA does seem to be IMPROVING. Slightly. It'll take until the next few game releases to see for sure.