The exact meaning of a ‘dead level’ depends on who’s talking. I’ve heard a number of different definitions:

• A level where the only improvement the character benefits from is increased HP. Typically used for oldschool games, since I don’t think a level like this ever exists in D&D 3.5 or Pathfinder.
• A level where nothing improves about the character save for basic numbers stuff, such as HP, Saves, and Base Attack Bonuses.
• A level where the character does not receive any new special abilities, though they may increase their HP, Saves, BAB, Ability Scores, or number of feats.

Here, I’ll be using that last definition, since it is the one which is most relevant with regards to the changes made between Dungeons & Dragons 3.5, and Pathfinder.

Back when I started playing tabletop games, around the advent of D&D 3.5, I often felt as though my character’s progress was painfully slow. I was excited to become more powerful, and nothing was worse than leveling up and realizing that very little had actually changed for my character. Dead levels were a serious frustration, because at that time planning out my character’s mechanical development was important to me.

When I originally read the Pathfinder rules, I praised them for the way dead levels were eliminated from the game. It meant players could spend less time waiting, and more time improving their character’s build. And I was right. Pathfinder does allow players to spend more time working on their build.

This is a good thing, because a big part of the appeal for RAW 3.5/PF is building your character. If the players are playing to build characters, and they almost never get to do that, then the game isn’t providing a satisfying experience. Dead levels are a huge issue, and should be eliminated.

However…

I no longer enjoy building my character. I’m not interested in playing a tabletop game where this is my goal, and I’m not interested in running a tabletop game where this is the goal of my players. Such gameplay is perhaps better suited for a video game or board game, where rules are more clear-cut and easy to enforce. In a tabletop game where the rules ought to be flexible and players are owed a logical explanation for any limitations placed on them, I don’t feel that it works.

So in the type of game I like to play and run, what is the point of leveling at all?

Improvement can be valuable without being the focus of attention. It can even be an important goal for the players without being the focus of attention. My goal is to provide my players with a game where they feel as though they can work towards any skill or goal diegetically. The advancement granted them by their class should be simple and easy to record & remember. More individualized character improvement can be sought out through gameplay, regardless of whether the character has leveled or not.

Dead Levels are only a problem if leveling up is the only means of improvement your characters have available to them.