The speakers in these and in the WH1000XM3’s are actually the same. The difference is that in the MDR-1AM2, your device’s amp powers the speakers directly, vs the amp inside the WH1000XM3. This ends up making the MDR-1AM2 set sound better, cleaner, and more balanced.
However, know your market. These are designed for audiophiles, not general consumers. Most people willing to spend $300 will only do so on headphones with Bluetooth, active noise cancellation, and settings in an equalizer app and such. Thus, making the WH1000XM3’s more popular.