Ok i have to weight in more.
First off, personally i prefer the old system. It was entertaining, the number of materials in the whole game didn't surpass like 15, the potions made sense (so no sticky sunscreens and such), you could sell the potions and the whole circle of materials/potions was a working economy, it was entertaining and fairly difficult, the potion rarities were really nice, the system itself was visually pleasing and i don't think it was difficult to use, it did have a small learning curve (learning to use temperatures, and learning the recipes) which is another plus in my eyes.
The reason (that we often hear/used to hear) that it got removed is that it was laggy, which is veryyyyyyyyyyyyy debatable. I could never brew legendary Felix (i did get a unique one, which is the tier before legendary) but my argument is that this new system isnt any less laggy or ping friendly, it's just that the rarities and extremely short time frames are gone. In fact, i think the hologram system is more glitchy (during butterbeer event 2022, those brews had rarities too and it just proved that the new system had the same issue as old one, if not worse).
Another reason which isn't really talked about, and I'm saying this allegedly, the old plugin wasn't ours, and the guy who made it didn't update it. And knowing pw, they want to have their own things. Therefore, a new custom plugin was made.
Now I spoke to a staff about this, I presented them an idea I had (for the potion system) that I still think it's great, but i was indirectly declined. Their goal is to find balance between an entertaining system (with many steps, possibly a learning curve etc.) but also an easy system that new players can understand and not rage quit. It appeared my idea wouldn't really be new player friendly.
Anyway, at the end I will say that old system was better and many people that raged on it weren't new people that didn't understand it, but people who's let's say, couldn't get the legendary Felix or people who rushed brewing and then failed. Also, if it didn't have rarities and time frames, it wouldn't be "difficult".
But generally the things that make the old system better in my eyes, and that I would like to see in the new system (idk about the mechanic, but the system will be new nonetheless) is
1. A more visually appealing system
2. System with lesser materials and useful potions that make sense, which you could possibly sell
3. Having recipes for potions and not just blindly jumping into brewing
4. Something more than just clicking the steps in order, in old system that was the temperature and stirring ig.