The reasons its "still" so buggy are explained to you in the video displayed as your downloading/installing. Unless this is different for everyone.
Its only a small team and rather than sit on it for ages it was released as a "beta" early to get feedback. This discusion between devs and players is then used to update and alter the game.
With regards to the specific bugs mentioned above ^^. PVE is not currently the main focus of the Devs. Its been enabled so that you can see the environments, features and gameplay but there is only about 1 hours worth of questing until you run out of stuff to do. There is a single daily quest and some random repeatable events but thats it.
Most of this repeatable content is hard to do solo, so if your a lone PVEr this isnt the beta for you.
This repeatable stuff ^^ allows you to grind/farm the resources you need for the crafting system. You then craft gear, weapons and consumables to help you in PVP.
This is why when you log on for the first time the starter zone outside of the city seems full of life and players. Its pretty much just people in "thumper" groups farming materials.
The focus is on PVP so the only bugs being fixed are PVP ones.