GGG is trying to add something that isn't just another Breach. Density creep seems to be all the community really asks for anymore. As much as people bash leagues, I don't really often see the community discuss what they would like to see out of further leagues besides regurgitating "breACH!!" If you need poe currency cheap in game, you can choose u4gm.com sale cheap poe currency.
It provided tons of cool things such as:
1. Flask crafting- remember spending all your alts to try and hit that Chemist's of Heat flask, only to message 10 afk people and end up buying it for 10c?
2. Imprinting of blue items - super nice having multiple chances to hit that regal on your dream item
3. Remove/Add Prefix Suffix - annul/exalt in one!
4. Adding a specific stat to an item while preserving prefixes/suffixes - INSANE crafting potential. It can be argued that this was way too strong and huge power creep, as it allowed for much cheaper crafting of godly items. It did have a downside of potentially bricking your item by locking affixes. You also did have to use red beasts of appropriate ilvls for the craft.
5. Mirroring flasks - Perfect QS and jades for everyone! I made a large amount of chaos throughout bhc from mirroring my perfect alchemist's adrenaline quicksilver. It was a neat experience getting to host a "mirror service" for once.
6. Horizon orbs - easier atlas progression and much less buying/trading needed when chasing red/t15 elder/shaper guardians. Very useful for SSF as well
7. Access to talismans - did you know you could farm Pen for tons of canines to use for the t2 talisman recipe? I filled the rest of the recipe with the unique from A6 coast. I sold ~10 talismans I farmed for 50-200c each
8. White sockets on non corrupted items!
9. Allowing another way to target farm uniques through specific ilvl red beasts
10. Aspects and having items that alter how they work (without just giving straight-up set bonuses) were super neat
So yeah, these are all pretty dope imo. I hope some of you feel the same way. If my bias isn't obvious, I LOVED Bestiary. I haven't had this much fun playing the game since....breach. GGG wanted to provide us with access to all these things to add depth to the game.