Apple Bloom's Cutie Mark Should've Been A Hammer Because She Did A Awsome Job Fixing the Clubhouse. Sweetie Belle's Cutie Mark Should've Been A Microphone Or A Music Note Cuz she is Great At Singing, Scootaloo's Cutie Mark Should've Been A Scooter Because She Is VERY GREAT Doing Tricks on her Scooter

What do you Think?

I mostly agree. I think Applebloom should have had a potion making cutie mark and Scootaloo should have had a mark related to some type of ground based physical activity, maybe a running cutie mark, or scooter.

The shields represent their shared destiny  
The music note represents sweeties love and skill for music, the star represents her!  
apple blooms apple and heart represents her love of her family and the apple itself, kind of runs in the family
scootaloo well she loves going fast and doing stunts, if the wing and thunderbolt is any indication

as for your post
one sweetie cutie mark does have a music note
two apple bloom getting a mark representing her love of family is much more fitting not mention wholesome
third scootaloo was always a stunt pony that's hard to represent

if I hade to guess Hasbro was trying to design marks that both represented them and their purpose

and final note on marks

destiny identity and talent! 
you get your mark when you figure out three things,
where you fit in amongst everyone else, what your good at, and who you are.

but some marks lean towards one of the three the CMC literally have a perfect balance of all three. making them perfect for the role they hold

https://docs.google.com/document/d/1vqeHezuBjnwyTM_1fVE4O_00WDoWe_8dI1H1YwQ_CMg/edit?usp=sharing

7255159
why change it are you writing something?

7255158
Yes! I agree full heartedly!