The high critical temperature and magnetic field in cuprates and Fe-based superconductors are not enough to assure applications at higher temperatures. Making these superconductors useful involves complex and expensive technologies to address many conflicting physics and materials requirements.
@article{arxiv.1109.6307,
title = {To use or not to use cool superconductors?},
author = {A. Gurevich},
journal= {arXiv preprint arXiv:1109.6307},
year = {2015}
}