This post contains several ideas about troops and troops levels in various areas of the game. I got my primary inspiration by donations, but I then extended my ideas to the actual gameplay.
First of all, a common issue in donating troops is donating the wrong troops, accidentally or otherwise: it is the proverbial situation when a player asks for a level 3 dragon, only to receive a level 2 goblin. I think this is simple to avoid. When a player wants to request a donation, a menu will open up and the player will be able to select exactly what kind of troops and which levels he is willing to accept. This menu will be similar to the menu a player gets when donating troops, in which one simply taps on the troops one donates. For example, a player will be able to select level 2 pekkas and level 5 wizards only in the list, and this message will be broadcast in the chat. If another player attempts to donate a level 7 barbarian, the system will not allow the donation.
Now, consider a player asking for a level 2 dragon, and assume I have level 4 dragons. Sure, I can donate and fulfill the request, but I am over-fulfilling it. The requesting player does not need such a high level dragon. So, why should I not be allowed to donate a level 2 dragon? I do not need to pay the extra elixir to build the higher level dragon, since I do not wish to use it in the first place. So, I think I should be able to choose the level of the troops I build: if, for example, I have unlocked level 3 dragons, I should have the ability to build a level 1, 2, or 3 dragon, but not a level 4.
Finally, how many of us TH 9s or 10s actually feel nostalgic for the days when the gameplay was simple, like in TH 5 or 6? Now we just skip these bases as the loot, because of the loot penalty that applies, is infinitesimal. But suppose that we get the ability to select the levels of the troops and the spells we build. Say I am a TH10 and I have built an army of 150 level 3 barbarians and archers, with 2 level 2 healing spells. It does not matter that I am a TH 10; I am not attacking as a TH 10, but rather as a TH 6. When I go out for a raid, the system could detect this and consider me a TH 6 when it calculates the loot penalty. So, the loot penalty should not be a function of my TH level and the opponent's TH level, but rather of my army strength and the opponent's TH level. Even better, it should be a function of my army strength and the opponent's defensive ability.
To summarize, I have proposed 3 ideas related to troops and troop levels:
a) When requesting troops, a player should be able to make precision requests, selecting from a list exactly which troops and levels (s)he is willing to accept. The system would then allow only these troops to be donated.
b) A player should be able to select the levels of the troops (s)he builds, provided (s)he has unlocked these troops and levels.
c) The loot penalty applicable in a raid should not be a function of the attacker's and defender's TH level, but rather of the attacker's army strength and the defender's TH level.
What do you think?

