I disagree that this is at all bad.2. Most of the good suggestions to make high level fighters better result in diminishing other classes (e.g. granting expertise).
I think philosophically all non-casters should excel in skills if a caster is being dependent on spells for non combat capability and well that is what is mentioned usually when we talk about out of combat ability being better by casters they are no longer really dependent on skill, ie why would he in theory develop the skill?. A fighter could have auto proficiency in Athletics or even Expertise a wizard might require Arcana diminishing choice. And yes a rogue might do the same with Stealth (like the fighter not the Wizard).