Well, if you’re coming at it from an immersion/story point of view, the HEV suit is riddled with tracking bugs, so they would know exactly where you are at all times. But that is beside the point. There’s quite a few opportunities to sneak up on and surprise the HECU as it is. It’s only once they’ve already seen you that they start “aimbotting,” and that’s usually because they’re around that corner, or on that platform pointing their weapons directly at the spot you last poked your head up from - exactly as they would in real life. It just so happens that most of the rooms that contain HECU have them with eyes on the point you enter from - in the ones that don’t you can easily get the drop on them.
I’ve never felt “cheated” by the AI detection or accuracy in any way.
Also, I’m pretty much in agreement with the “MP5 HECU sniping from 400 yards” point. It would be nice if they didn’t do that in the larger open areas that allow them to, but if that was the case then they would need to be taking cover intelligently and not just running toward you to get in shooting range as that’d make them ridiculous easy to sit back and snipe. In fact, it’d be nice if they shot a few bursts of covering fire from range and then charged in to take cover.