Sure, being supersonic and agile can indeed maneuver to bleed out the energy of the intercepting AAMs, provided that the tactics and timing are right.Supersonic Agile planes are much more capable of outmanuvering missiles to bleed its energy. This is how modern fighters and fighter bombers deal with BVR missiles. BVR battle is not just about seeing enemies on Radar and shooting missiles. Its also about manuvering towards the ground to confuse missiles, using terrain, using chaffs and flares and also using specific manuevers to force the missiles manuever much more than the plane. Slowly BVR missiles lose energy and lose track.
Supersonic and Agile planes atleast have abilty to do these things. Subsonic slow moving bombers are pretty much sitting ducks when a BVR missile is shot against them.
Also another point is that most supersonic planes can actually outrun missiles, if they choose to flee the battlefield. Cause Missiles constantly lose energy due to air resistance and are only hypersonic in the middle-phase of their flight. Subsonic planes cannot even flee the battlefield and outrun missiles.
However, and similarly - The enemy side too can (and is/have) devising(ed) tactics and methods of their own in order to counteract and neutralize your counteractions. Who said that the enemy must fire their LRAAMs (and SAMs) at their maximum possible range, to begin with? You can choose how to fight - So can the enemy.
Besides - And arguably quite important - Trying to go with strategic bombers that have all of the following features:
5. Stealthy; and
6. Able to carry payloads equivalent to other strategic bombers (20+ to 30+ tons) -
Means that each of those bombers are going to cost an arm and a leg to procure, operate and maintain. Neither the US nor China are able to procure them at scale, because doing that will be very cost-prohibitive and economically-unfeasible.
In the meantime, I suppose you missed the "entire broad system of countermeasures that are meant to mitigate and minimize such vulnerabilities" phrase. There are way more things than just being a VLO design.