The magnet with the strongest magnetic field isn't necessarily the best engineering solution for a fusion reactor. In particular, these magnets need to be cooled (plumbing can be bulky and coolant can be difficult to work with) and allow for easy servicing of the reactor components (particularly the vacuum vessel which will need replacing every ~10 years due to neutron embrittlement). This magnet design is noteworthy because of several factors: high-temperature superconductivity means they're cheaper and easier to cool, the high field strength allows for a smaller scale reactor, and the physical construction of the magnets makes them cheap to build and allows for easy disassembly during maintenance periods.