Edit: Ha! you added to your post. That explains it.
You didn't, but a player maining ninja would. If you have the ability to run ST on a relatively geared monk (ideal as they share ST gear and you can need on the drops), then you can gear NIN quickly. But new players can't do that. I've been able to leverage an existing 50 to get gear for my alternate classes, this applies to the experience of a character without that luxury. That's who square has to plan for. So that gear is absolutely still relevant. Not for you or I necessarily, but definitely for a fresh 50.
To your endgame comment, No, you aren't in the same hole. Assuming you've farmed that content for gear, you are already positioned for the new content. Any players coming up the gear ladder have a slog in front of them that you don't. That's what keeps progression players farming the content.