That's why you have so many people who have it enable complaining about it. That's why you're constantly hearing people bitch and complain about getting ganked. Figured that was pretty obvious.
Idk about other areas in the world but where I am, Alliance has a constant 30% leveling buff since the changes to it. If you want people who complain about warmode out of warmode, tell Blizzard to not make it stupidly lucrative. 30% exp + 5% form the JC gem puts you at 35% exp bonus. That's 10% less than a set of heirlooms. Of course people are going to turn it on, they'd be crazy not to. I personally wouldn't level without Heirlooms and since they wait for several patches to turn heirlooms on for the current expansion, why wouldn't someone have it on if they were leveling? Hell even when they enable heirlooms for BFA that's STILL and extra 30% for leveling on top of your heirlooms.
Warmode should only be there for people that WANT to be there. IE people who want to sit around and camp each other all day. There shouldn't be incentive for people to turn it on other than they enjoy pvp. Does that mean there will be way less people in WM? Duh. Will it be harder to balance? Yep. Yet those are things they should have thought about before taking away pvp servers. When it was 10% flat bonus it was helpful, but nothing major. When you nearly make it equal to an heirloom set however, you're doing it wrong. If you want to argue they don't 'force' you into WM that's fine. Delete your heirloom gear and never use it or don't because you'd be stupid to do that just like you'd be stupid to pass up on the 30% exp.
For most people leveling is a means to an end, something you have to do in order to do the end game content. The first time you do it, you may listen to all the quests for the story but after that you just want to get it done.
Edit: I know this argument is stronger from the Alliance point of view. Seeing as if you're Horde you get a measly 10% since it has to do with 'faction balance.'