You seem to confuse gear progression with having end game. But there is still gear, just not an endless ilvl increase with each new content. Gear progression is horizontal (I think), i.e. different distribution of stats, fun stats and procs (
example). Of course, equipping the right gear is still important, it is just not possible to completely outgear someone. Look of gear is also very important, and a way to show off your immense skill so to say. PvP awards you glory, which can be used for new armor skins, again to show off your skill/or dedication to PvP. There is no stat increase because that causes gear > skill (BG gear, Arena gear, newest seasons gear). Other important things I can think of atm are: having fun, improving yourself, experimenting with skills/gear ...