Tradeskills are way more useful in LotRO than in, for example, WoW.
Up until approximately level 50, when you start getting legendary items, crafting is the way to reliably gain access to best weapons and armours.
This is completely different from WoW, where major items are obtained through random drops and instances.
In LotRO while levelling, you can with few exceptions safely vendor-sell any piece of armour/weapon that drops -- nobody will buy it in Auction House.
Instances provide weapons and armours that are comparable to crafted, so do skirmish marks. However, crafted items are for most part slightly better and usually way easier achieved. Crafting allows you to make exceptional (blue) items for every 10th player level starting with 20. These items are also easy to achieve and rarely have adequate counterparts available for skirmish marks or instance drops.
Considering that as crafter you can also easily achieve crafting of legendary items, it still makes a lot of sense to level crafting of the type of items you can use yourself.
You might want to check out http://prezi.com/hw0aez2lk8vt/lotro-crafting/
to see which classes can craft what items.