Gaining access to raw data is difficult. For example, if I want access to raw projection data on CT, it requires specific research keys and agreements with the vendor. A typical end user, like a hospital, cannot get to this raw data as part of a standard purchase.
The Cartesian (rectilinear) approaches to sampling k-space are generally very inefficient acquisition time-wise, but very tractable for a cheap computer to reconstruct via inverse FFTs. Non-Cartesian readouts (such as radial, spiral, etc) can radically reduce acquisition time (read: time for patients to lie in the scanner) but radically increase the computational complexity of the reconstruction. Estimates range from 1000x to 10000x times as complex if you use all the fancy stuff to maximize image quality and reduce acquisition time as much as possible.
There are numerous (solvable) technical challenges to implementing these strategies, but the biggest is financial. If one MRI scanner can do the work of 3 or 4 MRI scanners by moving patients through faster, that's a lot of lost revenue for manufacturers, so there's not much of an incentive to change the current paradigm.
If one MRI scanner can be more efficient, there is enough competition in the market for it to be wildly successful. The major vendors have enough technical parity for efficiency to be a key difference maker. Hospitals and health systems are the customer and they need throughput.