Instead of having Strikers walk as the same speed as guardian or recon give them an unmodifiable MSD Med.
Aims: Promote class diversity and reliability on teammates. Give Recon and Guardian the edge to take out strikers who use excessive boost. Make striker battles shorter.
Pros: Striker classes would have to be more careful about running out of boost since Recons and Guardians can now catch up to them (as well as enemy strikers with Boost).
Cons: Striker will have trouble running back to base to heal and this debuff will be unaffected by MSI armors like BK or Mercurials
Not actually a bad idea, however I would rather make strikers more glass than less cannon. Moving fast and attacking fast are sort of things strikers rely on for defense, similarly recons rely on not being seen and guardians rely on blocking the blows. Removing the capability to dodge is a heavy hit to survivability instead of their defense.
I would rather decrease striker defenses to be 50%-70% of the tier defenses, and guardian to be 120%-130% of the tier defenses.
I see what you're getting at for strikers and I think it's not a bad change, however it's not the change we necessarily need.