Some of the jewelry you get is purple. Deconstructing them gives you zircon grains, which are worth a lot of gold. Yes, you can sell them on guild traders or in zone chat. Farming and deconstructing jewelry also allows you to level jewelry crafting.
You need the right jewellery passives on your deconstructing character to get the maximum grains but yes it's worth it then - especially as an accidental sideline for levelling a new toon, and you can also sell purple stuff to people with the passives if you know them.
Alik'r isn't the only one worth farming, some other's have good sets you might want to actually use and all drop the same amount of blue/purple stuff. Deshaan for example gives you both mother's sorrow and plague doctor jewellery.
I don't think it is worth it. Questing and adventuring seems to drop as much jewelry as farming dolmens but is more fun. I think leveling 1-50 goes quickly enough that trying to collect dropped sets at an appropriate level is a losing proposition. I like to level up using a set of 5 crafted pieces and change them up for higher level of the same as I level and fill the other slots with whatever drops. That seems to work well up to CP160 in fact when all that changes and it becomes time to really put together some gear that you can use for quite some time.