Thank you for thinking thru this. But can you also take into consideration of BCX too instead of just purely level? This will also justify those half lvl up cards.
Using your example but with BCX assumption
Level 5 Common (60 BCX)
Level 1 Common (4 BCX)
Level 1 Rare (2 BCX)
Level 1 Legendary (1 BCX)
Revised
Another Example
Level 2 Common (13 BCX)
Level 2 Common (8 BCX)
Level 1 Common (4 BCX)
Level 1 Common (1 BCX)
Level 1 Rare (2 BCX)
Level 1 Legendary (1 BCX)
I kinda like this. The current "best practice" is to only upgrade to full levels, without blocking more BCX than necessary. And rent out lower-level cards (usually at level 1, thus why so many level 1s on the market, besides the actual demand which is for level 1s) until there are enough to level up.
What you propose offers an alternative incentive for combining cards without reaching the next full level, while being on the same page with what the proposal wants to accomplish: to determine people to combine their cards.
Interesting Idea
I like this idea but it will really complicate the markets as rental and sale prices are determined by levels and not bcx.
This is definitely a better and more fair way of doing it. It would encourage gradual levelling which creates scarcity as well.
But as more complicated (so longer to do) I imagine it will get overlooked.