An extra difficult lost sector is not end game material at all, its honestly another way bungie has figured out how to artificially extend play time for a player. Forcing a player if they want to get the new exotics, that bungie was so gracious in hyping up for the expansion, to spend more time grinding their light level up and be able to effectively beat them or the player can go in at a lower light level and going against another of bungies often used tools of artificial difficulty with bullet sponges and over damaging enemies time and time again until they finally beat it and pray the rng gives them the exotic. Plus we don't even know if the exotic drop is even considered a powerful drop when you get it.

Hiding exotics behind some harder content doesn't make them endgame content.