"What we have at the moment is a large number of different devices all stomping over the entire ISM band almost at random."
That's the purpose of the industrial-scientific-medical (ISM) band. Want to cook popcorn with a fuck-you-powerful radio transmitter? Slap a discount "shield" on an ISM transmitter and start zapping. Need to get telemetry out of a rotating machine? Slap a transmitter on it and make a token nod to shielding. Want to treat granny's injured knee with a radio diathermy machine? Just fire it up and start cooking the old gal.
There are good arguments to be made for creating managed unlicensed bands. But not at the cost of the ISM bands' free-for-all nature.