there is absolutely no synergy with progression through the 1-60 content and 1-300 professions.
i recently made a rogue and tried to match my leveling with leatherworking. the flaws i found that no matter what the gear i could make was always far below my level, and the mats required for the items my level were from content far above mine...
the gear doesnt match what is available from questing/dungeons anymore so basically you are just vendoring them. and the materials required are absolutely absurd.
the skins required to get to thick is roughly around 700-800... most mobs drop 1 skin, rarely i got a guild perk proc. and you need roughly 800-1000 skins to go from thick to knothide.
thats nearly 2000 SKINNABLE mobs you need to mindlessly grind for gear you are going to vendor anyways.
i would suggest severely reducing the amount of materials required for 1-300 or up the amount of skill up per craft, make the gear useful, or match the ilvl with the ilvl of the mobs you are farming the materials from. as of right now its a complete PITA and making my leveling experience horrible. i cringed at the thought of logging on my rogue this morning knowing i have to grind 1000+ yeti just get to Burning Crusade caliber leatherworking so i can progress my character.