Expertise Dice are perfectly fine as a shared metric (means to quantify a resource). Maneuvers (how you spend the dice) are what need to be differentiated between the classes.
There's plenty of room for overlap, but each class also needs ample space where they do not overlap so as to define their unique niche. In some cases one class will have a maneuver that is "just better" than a maneuver that the other class gets - and that's great. The Fighter gets a maneuver to use Expertise Dice to help with a skill check involving Strength, while the Rogue get a maneuver to help with ANY skill check. Cool. The Fighter gets Deadly Strike (expertise for damage) while the Rogue gets Sneak Attack (conditional expertise for the same damage). Cool.
They both get saving throw boost maneuvers and damage-deflection maneuvers. The Fighter gets blocking abilities and whirlwind attack. The Rogue gets movement tricks. That's a good framework even thought the Maneuvers List needs more work just like the Spell List does.
Similarly there's always been a bonus of overlap and non-overlap between the Wizard and the Cleric. They share a lot of transmutation, abjuration, and enchantment spells. The Wizard never gets healing and the Cleric can't cast Fireball. That's always worked pretty well.
As to "Fighter-light," I don't see that as being the problem. We can't have our cake and eat it too. If the Fighter is going to have all his talents pinned to the Combat Pillar and Rogues are going to dominate the Exploration and Interaction Pillars then when I play a Rogue I know I'm signing on to feel like an "also ran" in the Combat Pillar when it comes to Fighter Damage, HP soaking, and Armor Class. That's called balance*.
(* My dictionary also lists that word as a handy antonym to the words "Elminster," "Raistlin," and "Drizzit.")
I think real problem is that the Fighter is just pinned to the Combat Pillar right now - and in particular he's pinned to hitting things really hard. I think the game would be better if the Fighter had a better gift for "stunts" (athletic improvisation in and out of combat) and the Rogue had more utility for gimping enemies with his expertise dice - hamstringing, blinding, tripping, climbing-on-the-back-of-monsters-and-riding-them, etc. Fighters should impress in multiple ways on the battlefield, and the Rogue should be able to disable a guard, a lock, or the right eye of a Balrog with equal aplomb.
- Marty Lund