For levels, I don't think they are bad. But Like Zzer mentioned, I'd advocate going back and seeing why levels are used, their benefits and negatives, before designing a progression system. For example. Levels in Table Tops were meant to mark progression, but not with the end goal of ever reaching a max level. The differences between high and low level characters was far more subtle than most video games today. And the reality is, levels were used less as a gating tool for DM's and more to effect the narrative of the story.
In other words, levels didn't block content--they changed how players had to approach content. A level 20 vs a level 7 had to kill a dragon differently, but they could both kill a dragon, because the game world allowed for an infinite number of variables that the players imagination could exploit--the better your DM, the less relevant levels became. In video games, it's that lack of agency in terms of changing the world that really makes levels seem restrictive and absolute--and I suspect it's for that reason they have been relegated to nothing more than a treadmill to be completed and thrown away.
And on that token, I agree, WoW's levels, are pointless, they may as well not even be in the game--they are tired and meaningless goal posts that do nothing but obsolete content. But I don't think that means levels themselves are bad--rather I think it means systems around levels have turned them into something tired and boring. I think there are probably plenty of ways to go back and recapture that table top feeling levels had as a "road" rather than a destination--especially given the new technology that increases the fidelity of actions in regard to the world (So that cave? I can use it to change the way I fight, rather than simply being a stage to fight on).
Long and short, I do like levels. But I wish they were a lot "softer" in terms of their affect than current games allow. I wish there was more horizontal progression within each level, and the point of getting a level wasn't so much to get a direct power boost, but rather to gain access to that horizontal power.