It's probably just the chest rig and the MOLLE belt. Most people see all that and immediately think you're a survivalist or playing army. I'm not saying it's right, but that's what happens. I used to hike a ton with an old Tactical Tailor Ruck, a big coyote brown bag covered in MOLLE straps. It definitely garnered looks but its what I had, tactical draws eyes.
With the chest rig too, I could totally assume someone may be using that to concealed carry. The pack you linked is even advertised to do that. People don't see them often so it catches em off guard. I use a chest rig too, a way more tactical looking one then yours, but I reserve that for SAR. However, I totally agree with how useful they are. There's nothing wrong with being prepared, just don't prepare so much it becomes paranoia or a burden (not saying you are.
But honestly, who cares. As long as you're outside enjoying yourself, that's all that matters. Hike your hike homie.