I strongly disagree that dragoons are useless. They are THE most mobile class in the game and cannot be held in contest very long.
I'll again refer you to the breakdown that I wrote up. Our standard attack is extremely weak, our defenses are little more than what Samurai get (who trade in their defense for much higher damage potential), the sole damage skill we get (Impale) is one we don't get until 45 AND eats a stamina bar, killing our health regen (a key part of our selective engagement tactic) just as Jump did when you were experimenting with that.
On top of that, Jump really isn't that fantastic in terms of distance covered. In theory, yes, Jump is super badass and lets us do whatever we want in a fight. In practice, it's far from that. Before I even get into technical complications, something that most people seem to be discounting is travel time. Sure, we get a vertical boost and a forward boost, but it's not instant, and any class is able to start sprinting when we jump. This is a core weakness of Jump, as it has always been, and always should be. By the time we hit the ground and can run, the distance has been closed quite a bit. Sure, we can jump on top of stuff at higher levels (again, in theory), but that requires the terrain to be present when the fight occurs, not adapting to whatever is around. And, on top of that, even if there is terrain around that can be jumped upon, other classes are perfectly capable of climbing up while we're still in the air and unable to shift direction.
Then there's the considerable factor of technical issues. ANYONE who has ever played a Dragoon will tell you that lag determines whether we live or die when jumping. With the cooldown like it used to be, a jump that messed up because of lag wasn't as significant of an issue. With it the way it is now, a lag altered jump is a HUGE setback even for a master Dragoon. For those under level 40, it's a death sentence right then and there.
You assert that Dragoons are the most mobile class in the game (which they are not, by the way. Bards [who also hit just as hard as we do and have a large selection of utility skills both offensive and defensive] are. Even I couldn't catch one with the way Jump was in Zeal, let alone how it is now), yet there's a key factor that also must be addressed. "Alright. We're moving fast. Now what?" Ignoring the fact that Dragoon mobility has been nerfed exponentially, what else is the class intended to do? We have our gimped Jump. What's our role in combat? Our standard damage output is laughable when compared to all other melee classes. We can barely outpace DISCIPLES in raw DPS output when you factor in Impale and Smite, and they still have heals and forcepull/push in their arsenal, with their chance to instantly restore half of their full health if killed. Oh, and don't forget their FULL Safefall too. Defensively, we have a little more armor than Samurai and almost the exact same amount of health, but while we have no defensive skills, they have BLADE GRASP. While we have our Disarm that we can use for three seconds of safety, Samurai can go absolutely apeshit and slaughter everything with their MUCH higher damage output, and dedicated damage skills, while remaining practically immune to melee attacks.
Basically, what you have with the Dragoon class that has a little more damage than a Disciple, less survivability than a Samurai, and a gimped utility skill that's supposed to define our class like a Ferrari is defined by a Hot Wheels car.
While it's all listed in the article I wrote (which I IMPLORE you to read with an open mind), I'll post a smaller TL;DR here, with points assigned from most to least in terms of rank:
Warrior Class Offensive Capabilities:
4) Samurai
3) Dreadknight
2) Dragoon
1) Paladin
Warrior Class Defensive Capabilities:
4) Paladin
3) Dreadknight
2) Samurai
1) Dragoon
Warrior Class Utility Capabilities:
4) Paladin
3) Dreadknight
2) Dragoon
1) Samurai
-Point Summary-
Paladin: 9
Dreadknight: 9
Dragoon: 5
Samurai: 7
For those who INSIST that Jump is super powerful, let's take a look at the class ranks without utility skills:
Paladin: 5
Dreadknight: 6
Dragoon: 3
Samurai: 6
Look at the numbers. It's pretty obvious that there's more than a little bit of a gap here. The Dragoon class is indeed broken, and it's even worse if you consider how difficult it is for low level Dragoons to use Jump. Our offense is pathetic. Our defense is even worse.
Changes need to be made if you want the Dragoon class to be viable. The ranking order doesn't even have to alter, when you consider the huge distance between Dreadknight and Dragoon offensively, Dreadknight, and Samurai defensively, and Dreadknight and Dragoon in terms of utility.
Increase our offense, restore our armor, or restore our jump. The third would be the best option. Hell, if you want to see the problem firsthand, go in under an anonymous name and try to level the class yourself to 55 using no spawners other than the ones in Dragongarde that are the intended future method, and also PvPing while you do so. You'll see exactly what I'm talking about the first time you get into a fight with another specced melee class, and probably when dealing with a ranged damage dealer as well when you consider how many fireballs spell casters can hurl with their mana from level 1 and how fast due to the low cooldown.
EDIT: Saw a couple new posts after making my own. First, if you haven't played a Dragoon under the current system, then you have no qualification to talk about how our class performs. Second, with regards to using Jump to pursue, I'll refer you to my above point that Jump is not as fast as people think it is, and if you ARE able to get up close in pursuit, the pitiful damage you put out makes it extremely difficult to bring down an opponent, who can just ignore you and keep running to outdistance the huge cooldown on Jump now, or in many cases just turn around and kill you. Third, in order to get an opponent to run, you have to deal enough damage to them to bring them down to danger levels, which again, is extremely difficult to do with such a low damage output, and our new lesser armor decreases the time we can stay up close in order to do said needed damage. The "Jump away and regen health" option that I know someone is going to make is completely invalid because the small damage we do over a lesser time, makes us jump away faster to regen our own health, while our target can do the same, at the exact same rate.