Legendary items are not required to do any content with in the game at best they are a quality of life items with some flare added in for visuals. They are however meant to be worked for either buy grinding the various modes for either gold to buy precrafted ones or the mats to craft it yourself. The gift of the mists is not hard to obtain at all the only component that does require a little bit of time investment is the gift of battle which is only obtained via the WvW reward track. The Gift of Glory requires 250 shards of glory which you can buy off the TP currently 66 copper a shard. The Gift of War requires 250 Memory of Battle which you can also buy off the TP for a mear 5 silver per memory, but you'll end up with 250 or more just by spending time in WvW to get your gift of battle. The last thing you need to obtain is the Cube of Stabilized Dark Energy which the Stabilizing Matrix can be bought off the TP and the Balls of Dark Energy are just from salvaging ascended weapons and armor, rings and trinkets as well but they have a very low chance of dropping a ball. Yes, the legendary items are not unified in the requirements to craft them but that's what makes then unique.