Why are there no sources of EXP for crafters below 50?

[Jojoya]

Quick synthing mats then making one of every item in the crafting log for the first time completion bonus is a fair chunk of XP toward leveling. Don't worry about whether the result is HQ (unless you're going for the leve turn-ins) but do try to increase quality as much as you can since that impacts how much XP you get for making an item.

As Deathgiver says, I wouldn't push to level right now unless you have a specific reason to. Wait for 5.1 when they're going to implement an overhaul to crafting to make it easier for players to get into it.

Now I think about it, it's rather curious they only applied the 75% HQ bonus from using all HQ mats to ShB recipes (which are by a mile the easiest to 100% from NQ mats), instead of everything below which would be a nice boost for levelers. They got that a bit mixed up.

Even at low levels, XP earned is based off how much the player increases quality during crafting and not the end quality. I figured that out when I started on my third character and focused on making housing items to level. I don't feel it's a bad design choice since it emphasizes using your CP effectively to get quality over relying on HQ materials. It does make things a bit harder for the novice crafter trying to figure out how it all works.