Heritage began with an arrangement with Schaller for pickups and hardware. I assume they got some discount for bulk purchases. But there were some complaints about the pickups, not the engineering but the tones. Decades later, I believe that they are pretty decent and have more options for adjusting the heights. I think that many had a prejudice against them or simply wanted to personalize their guitar with the pickups of their choice, often expensive ones. Nowadays I don't hear as many complaints. Of course everyone can have an opinion.
Here's a comparison with Seths v. Schallers.
https://www.youtube.com/watch?v=9mURVofPTnY