Sure, it's nerdcool and might get you a slightly better fit to your face, but it makes it much harder for people to try their friend's headset and say "whoa! I need one too!"
Optimizing for virality as a consumer product designer is pretty much always the right business decision.
I haven't been anywhere near one of these units, yet, but I found this explanation highly compelling: https://youtu.be/mieWJ9vupqw?t=228
This is a design tradeoff.
The few times I tried VR headsets I have to say that I was annoyed by the adjustments and the cheap/weak materials that was used, also I noticed some drift after a very short time (likely due to wear for a demo headset, but still)
Not sure if custom made is necessary, but like with any eye wear, the correct size and alignment should probably be built into the device itself, it is more practical and durable.