Not because its lucrative, but because its the only place you can meaningfully compete before you have the economy of scale that lithium-ion has.
If you drop the floor out of the that market, the other industries will come calling you.
Grid storage is all about the price per kWh. Sodium-ion batteries ([1]) might become a good fit, while they are absolutely useless for electric airplanes / drones.
Sulfur is an industrial byproduct – no harmful mining required. This drives material cost down to 0.20 EUR/kg (compared to state of the art cathode material NMC811 at 20.00 EUR/kg).
No NMC needed.
It's not like lithium-ion owns aerospace, economy of scale doesn't give it the required energy density for an electric 747. Though I'm unclear on if this development opens up that possibility either.