What logic lies behind Champion mastery points?

Why do I think CMP system is badly designed?

1. Everyone is able to easily achieve lvl 5.
2. Even if you got carried by your team mates but you fed so much you'll achieve tons of points.
3. There is no difference between lvl5 crest achieved in ranked games and team builder, they are exactly the same.

What should be implemented to make CMP system MUCH better and more fun?

1. Implement negative points if players KDA is bad. (This is ''the MUST'' simply because bad players will not achieve bonuses or positive points if they get carried)

2. Keep the amount of the gain points (lost game) as they are.

3. Implement bonus points for players who had positive KDA even if the game is lost. (I can't see how it is fair if 1/15/3 player gets the same amount of points as his team mate who had 6/2/5)

4. The color of the diamond in the middle of the crest should be different if player achieved CM lvl 5 in ranked games simply because the skill level is completely different. There is a big difference between the guy who spams Vayne in normals and the guy who spams Vayne in Diamond+ so their crests should look different.