Some players use professions to make pants...and in some cases many, many pairs of pants.
Now, this is good news for non-crafters - the price of the pants is quite low - maybe 18K or so, so everyone can easily afford the best pants available (not so great for the crafters, because the profit margins are very slim, but well....)
The best pants for most builds are Shimmerweave Pants +1 (for SW and CW), Adamantine Pants +1 (for OP, GWF, GF and DC) or Drakeskin Pants +1 (for HR and TR).
All those pants are IL 510, but they have one annoying problem - they are all "blue" quality.
Now, this strikes me as wrong for two reasons. First the pants have a higher IL and better stats than "purple" IL 500 pants like the Lower Primal Paints or the Chultan Merchant pants.
Second, crafters used to be able to make "purple" pants - for example the "Prelate's Gemmed Exquisite Elemental Chausses" (or something like that), and making the best pants only "blue" quality just feels wrong - they used to be purple for a reason.
There is also the issue that many people like to use the best gear available, and having to use one "rare" piece where everything else is epic, legendary or mythic is just...well, annoying.
So, the IL 510 gear should really be "Epic" quality.
Remember: This is a game...it is supposed to be fun...