The argument that "our system is already bad so we should just merge this new bad component because it doesn't make it worse" is bad in software, and unacceptable in medicine.
If the scanning process has a sensitivity of 99.999%, and the next stage in the signal chain has a sensitivity of 50%, and we consider what happens if the MRI sensitivity drops to 99.9%, that's well in the noise in terms of diagnostic value. Use some of the extra money freed up by doing the MRI 10x faster to pay a radiologist to look at the scan for 10% longer, and perhaps the net accuracy has improved.
What is unacceptable about this kind of holistic reasoning about the system? High performing systems are frequently not composed of perfect components.
Omitting 90% of samples (based on 10x speed claim) leaves an awful lot of room for bizarre errors.