All the pluses have minuses.

The high speed means they radiate in the infrared like a small sun: even a small IR sensor will see one coming if its in line-of-sight, possibly hundreds of kilometers, because the flight path will have to be in the stratosphere for any reasonable range.

The same heat means that the missile itself cannot use IR sensors for detecting defensive missiles – only heavy power-hungry and probably limited view radar.

The maneuvering capability is relatively high compared to an ICBM warhead, but not to much else. At Mach 5 the turning radius is huge for reasonable gee loads. The shape is optimized for cruise after all, the weight budget for, say, 50g popout wings, means a comparable loss in fuel, or payload, radar, or anything else because of the sheer weight of structure required.

And, btw, ramjets and scramjets are notoriously finicky with respect to inlet flow angle-of-attack.

High gee means a huge loss in energy: if you start a 10g and 180degree turn at Mach 5 a gliding vehicle will probably be lucky to be supersonic at turns end.

And then there is terminal phase targeting. A whole new can of worms at hypersonic speed for the missile. All weather means you will be using radar, and radar means emitting, and emitting means you can be seen and killed.

If you drop to mere supersonic and below speeds to usr IR and Optical the defenders can use well understood weapons and tactics against you.

Maybe ALL these issues have been solved…but then again they may just remain niche weapons.