Why have modern jet fighter designs dropped the nose air intake?

I’m not sure stealth has much to do with it, or else Boeing would have never contemplated their F-35 design (I don’t recall there ever being a contention that their design suffered in stealthiness compared to the LM submission, even with the gaping Billy Bass mouth).

Also, as far as nose radomes are concerned, that’s going to be less of a concern in the future as more planes introduce electronically-steered phased arrays. No need for a swiveling dish of any size under a radome, the radar can be part of the aircraft skin.