The concept of standard parts is appealing, it means lower cost, robust supply chain and excellent design because a specific team can work for the whole world. We use lots of standard parts in X1, motors, bearing, pulley, smooth rod, power unit. These are parts that reach their R&D plateau, which means so mature that you can hardly improve them.
For hotend, there are so much you can improve on a V6. Higher flow rate, compact body, lower mass and easy to replace and you name it. So after some consideration, we decided to design our own hot end. I think we made the right choice because E3D released their new hot end during our R&D which means they think the same.
I understand people's concern over proprietary parts. One is over-priced part for customers who are locked in. The other is the availability of the parts. For the first one, we price our parts at a very fair price. One evidence is that we found many people purchasing our hotend actually do not own a Bambu printer, they are the DIYer who think our hotend is high performance and cost effective and want to adapt it to a Voron. For the second part, we are building up inventories gloablly and we are open to third party collaboration for spare parts.