I've never asked for vertical progression but what I do ask for is incentive. Incentive does not necessarily mean vertical progression. Incentive to *play*. A piece I read earlier in this thread about choices, I found to be a very good one illustrating this point. Currently there is hardly any choice. You throw a few traits together and boom, you've got your prof sorted out. You hit 80 and grab a few gold pieces and boom, you're at the power plateau. You do one PVE area of DE's, and that's that because all the others now are repetitive. You run WvW for a week, and you realize it is actually a pretty worthless perpetual power struggle for... nothing but a few percentiles of bonuses on stuff you'd hardly ever notice.
Incentive in a game should be: being able to beat some new bit of content because you mastered that which came before it. Incentive is being able to progress further because you as a player actually gained some insight and/or skill. All the arguments people speak of considering the state of the game are true - but the conclusion some or many of these people have drawn is outright wrong - they concluded WoW or the WoW players are to blame for this. They are not. Anet is. And I doubt Anet is looking to create a WoW clone, but I am confident Anet is completely out of options as to how they should create incentive to play without some fundamental changes to this game's core mechanics.
The best incentive to play a video game is to be better than everyone else playing it. Arena Net does not seem to understand this unfortunately.