The tiers* haven't really changed that much (except that the disparity is a bit less), however that never made the game unplayable.
In my own personal experience, the casters tended to be much more necessary because of their unique problem solving skills, but they could never just do everything on their own, and so still needed others on hand.
The game is designed more around the action economy and "4 main roles", such that a balanced 4 person party is often the most successful across the widest variety of situations.
A lot of the complaints I've seen about castes vs non-casters is from posts or comments that start with "The rules say...", or "I played one session and...".
These are often either unique or rare occurrences that people get up in arms about, or more likely, just theory being tossed around without seeing what happens in actual play. Something might look horrifying on paper... but plans never survive first contact with reality, because abilities and spells can't be looked at in a vacuum.
As for how things are in Pathfinder...
- Melee classes were given a boost up in abilities, especially later in the game. Many got new endcap stuff that are along the lines of save-or-die.
Most got new abilities that made them more versatile, instead of just more bonus (directly affecting how they fit on the tiers).
- With skill consolidation, the elimination of cross-class skill costs, retroactive skillpoints on Intelligence bonus, and favored class bonus all made it so pretty much anyone can be more versatile (skills-wise) than before, which helped the 2 skillpoint classes like the Fighter or Paladin.
A human fighter with 10 Int can get 4 skillpoints per level, and putting points into non-class skills only means he's behind by 3 points.
- While casters got some class abilities and unlimited cantrips, this only really improved versatility at lower levels (where they didn't feel quite so magical).
On the higher end of the scale, many "encounter-ending" spells were toned back with either changing away from automatic success, or adding in extra saves, or basically allowing additional methods of surviving.
For example, a death spell might have been changed so that instead of "target dies", it does tons of hitpoint damage, which can be mitigated, survived or otherwise circumvented (like a shield other spell).
All these play a factor in making casters a little less "all powerful" and non-casters a little more "capable". The tiers are still there (Wizards are still batman), but playing a straight classed Fighter to level 20 no longer feels like playing a chump.
*For those who don't know what I meant by "tiers":
It's the idea of rating classes based on how well they can handle a wide variety of encounters or situations. Casters tend to favour highly on such a scale, because the way spells work, you've got a lot of options. Feats and skills tend to be static once gained, and so non-casters tend to be on the lower end of the scale.
