The funny thing about crafting. Is that you can actually still mod just by finding the mod for it and detachching/reattaching it (I actually do not like this feature because once I found out about it it really cheapened crafting for me).
Crafting only gives you more control over what or rather when you get a specific mod. Secondarily, weapon mods aside from those related to damage have no affect if you use VATS.
Crafting is cooler since "you made it", but you could also get away with slapping some points into caps collector/fortune finder/scrounged and be swimming in enough caps to buy just about whatever and for-go the whole trash collecting/crafting side game.
Vendors also sell some very powerful unique armor/weapons.
I'm still on the fence though about which is better.