No really – I’m asking myself this every time I create something, then step back and am like:
Umm.. Why?!
This sucks!
What shall I do with this now?!
I can’t frame it!
…
The truth is.. in theory it says that contrast is a powerful tool. True. Indeed. Contrast can be used to create a better composition,  to create a dynamic, to draw attention to the focal point etc. 
In my case : I have no idea. Honestly. The eyes see and the hand grabs the brush and just sticks it in some paint which is attractive to me at that certain point. No plan. No prediction. Pure creative flow.

On one hand its good, on the other – I struggle afterwards. That I didn’t prepare any examples or pallets. And I set the work aside. At least I have learned to not throw them away anymore. sometimes it takes up to 2 years!! to finally see the work. To see what I have created and be like: 
Oh! Hello?! Well I have a frame for you, dear!

Or: Hm, I could add some details with pencil here.

So I guess the answer to my own question for now is: Don’t worry about it! It will come. Take your time. Set aside. Look at you – you are so full inside (you probably couldn’t match my work to my exterior FYI), its the creative outburst! Love it! Enjoy, experiment! 

I mean – my daughter is using contrasts and I freakin’ love it! In general I love how kids create. It’s amazing! I should learn more from them.