I feel like being able to swap cards in and out of the leader deck would be very useful. I realize you wouldn't be able to move equipment cards in and out without changing equipment, but I feel like being able to edit the learned leader cards would be very useful. Some of the weak cards you start with just become clutter in your leader deck later in the game.
Ability To Remove Leader Cards From Deck?
Yeah its a tough call. I think a good happy medium would be to have a max leader deck size. Once you hit the size cap, you have to forget/remove a card to add a new one. This keeps the deck static while still allowing for improvements and modification over time. This would add the additional decision of not only which card you want, but which one you want to replace.
You could also have the deck cap expand with player level if you wanted to allow for larger decks later in the game. I will say though, I have played a lot of TCGs and you ALWAYS want the smallest deck allowed. Going over the minimum cap inevitably leads to inefficiency and lower performance, so theres that to consider too.
I agree with you here. I think the lack of card options for the leader deck (at least initially) means little to no fiddling where as the large number of options for the follower deck leads to more need for customization.