Why is 箇 abreviated as small カ/ケ?

It isn't that complicated a character and it's taught in junior high school apparently. Why don't they just write the thing in kana normally or create a proper simplified character if it's really so much effort to write? Also for 一個 occassionally, and are there any others? Also why is it 1ヶ月 when its か but its ヵ所?

by qwerty889955