The lack of gear drops in the crucible really hurts, since it was the only reliable way to find some really fun weapons. Adding loot drops back to the crucible directly might be distracting and overwhelming. Instead, giving the seneschal a typical arpg-style gambler shop would allow players to get different weapons they want to try, keep the Skinner box rng effect and provide incentive for more crucible runs. The currency could be the green currency if the devs want to keep it contained to the crucible or fallen embers if they want to encourage playing outside the crucible as well. One way to make crucible runs even more worth it for people who already have good exalted gear would be adding the chance of unique affixes (maybe that exist separately from standard enchants) to gambled gear. Making them build specific (20% damage to enemies with plague; enemies take 20% more damage from ranged attacks after being hit with a bow rune, etc.) would be even spicier.
As a number of others have pointed out, the crucible has gotten longer and harder, but offers significantly fewer incentives. Adding a new, unique way to get good items will encourage players to actually engage with the awesome new content the devs have added to the game.