How do you play this game then? The point of getting gear isn't just simply "getting gear." to people, nor the purpose. It's a mark, an indicator, that you have completed this difficult portion of the game. On top of that, it also contributes to your character becoming better equipped for harder content.
Endgame content where you get the better gear always has a place in the storyline of the game. At least as far as the MMOs I've played. And interesting locations & enveloping storylines are fine... but if there's no reward, the mass population simply isn't going to do it. Risk vs. Reward.
And if, as you propose, we were to adopt this system of "needing" the best gear for certain content, then you're segregating a large part of the community, causing grief amongst players for not being allowed, or invited to, certain events. The best gear shouldn't give you elite "only I can do this status," it should simply make your character more efficient.
This is actually false. There's a very large difference in your utility as a player between 45 - 50. Because of how physical levels currently work, your rank is one of the few things that determines your characters ability to perform. Gear, stats, etc. have yet to be tweaked properly for the new battle system. Maybe you can equip -certain- BiS (Best-in-Slot) pieces currently, but any of the rank 50 items that drop from the new 45-50 instance require rank 50 to wear. Also it's been known that they are implementing level & class restrictions to the newer gear coming out.
That's the best thing you said in your post, though it goes against all the complaints you addressed earlier. Fact is, you're playing an incomplete game. People seem to have a really hard time wrapping their heads around this fact. The game has many more adjustments, tweaks, additions, removals, etc. ahead of it. Voicing complaints on aspects of an incomplete game which have not yet been fully addressed is silly.