Hello, the strange German dude,
Of course, implementing what you're talking about in Screeps is not an option. This change would decrease the number of tactics and use-cases of spawning and boosting mechanics (the example is, you can spawn 6-9-12 50parts creeps, renew them to have the same ttl using the spawner, then boost with labs), increasing logistics difficulty at the same time. This is exactly opposite to what we're trying to achieve in game design.
Regardless of that, I thank you for wording your idea here on the forum. While it can't be directly applied to the game, it still can be the source of inspiration in some other activities.