Jumptroopers are vastly underpowered

Agreed. Their rocket launcher has to hit dead on to do some damage. If you miss by a few pixels, the damage dropoff is enough to deal 10 damage. If they could just increase the AoE of the rocket to a value between the current situation and the Beta, then it would be much better. 

A good rocket jumptrooper almost never uses his rocket launcher (painfully true)

For me, it's fine that they cost 2000 BP in GA, but the amount you earn with them is extremely low. It is almost impossible to earn 2000 BP back by playing them. It feels like a very wasted investment of BP. I understand they implemented this so that players couldn't select the jumptroopers all the time. What this situation actually created, is that jumptroopers are only picked if hero's aren't available at the end of the game. My suggestion would be to increase the BP gain for jumptroopers in GA and implement the cooldown system from the LAAT so that you cannot pick the jumptrooper again if you just died with one.

Why is it that you can gain BP easily by playing with the AT-ST (low risk), while the jumptrooper requires risks and gives almost none...?!

Jumptroopers are one of the most maneuverable units and the most damaging you can get. You can cause a lot of damage just using the environment properly. I use rocket launcher only during flight over and finish of with blaster. Best are the clones, then droids, rebels/resistance and last empire/first order.

If the BP was earned reguraly, normal trooper player would stand no chance.

As for the tanks, they have been nerfed to make them seriously vulnerable; they are big and not maneuverable and die quickly, especially against heavy fire and exposing weak spots.

I wish the developers could give us some proper insight in how much jumptroopers and enforcers earn on average compared to the ground vehicles (average on all the maps and factions). 

Also the exact time when someone picks the enforcer/jumptrooper in GA (which phase for example) would be interesting (, this number must be corrected by the number of BP a player has available).

The BP gain of enforcer/jumptrooper does not affect any gameplay @Rogue_Manda_YT, normal troopers would have the exact same chance as it is currently in the game. The enforcers and jumptroopers are build in (in GA) as a 'final class' (such as the hero's), instead of them being a 'grow' class (such as vehicles are now) which can be used to further earn the BP. It would be better if DICE implemented a cooldown system on choosing jumptroopers/enforcers so that players can't select them after they died with them (which is already currently in the game for the LAAT).