I've noticed this has been requested on a few different occasions. However the requests have all been split up into several different suggestions, some requesting a new method of viewing cards and equipping them, some suggesting more information on them and others wanting the cards to be easier to manage.
I'd like to suggest if we could just get a completely new UI on the card system. Its good, but I definitely think it can be improved. It would be nice to have filters available, where you can search or click specific words such as ''Money'' or ''XP'' and it will filter the cards for you. Alongside this a new layout so all the cards are visible without scrolling. Then a method of clicking to view, and then clicking a button to equip or unequip.
My second suggestion is to request more information being available on the main character profile page (Inventory). It would be awesome to see crystal spawn rate, cash multiply rate and active shrines. Basically much of the information we find on idleon efficiency website but more available ingame, as sometimes the information on these websites isnt always correct. Its just so we dont need to switch around a website to find specific information that could just easily be displayed in the info tab. I guess its more for convenience, but it definitely would be appreciated.