Not just the Chassidim
Somehow the Chassidim get all the credit for the joyful spirit of Simchat Torah.
It’s true that Chassidism was known for its ecstasy in the presence of God and for practices that aroused joy and emotion. But joy in religion began with the Bible.
Not only does the Psalmist say, “In Your presence is fullness of joy” (Psalm 16:11), but he tells us Iv’du et HaShem b’simchah, “Serve the Lord with joy” (Psalm 100:2).
When the annual cycle of Torah readings became the norm in the Middle Ages, the annual arrival of Simchat Torah was greeted with rejoicing and all sorts of Simchat Torah customs developed.
In Spain the Torah crown was placed on the head of the Chatan Torah and the Torah vestments were placed on the people who read the Torah. Torah processions took place everywhere and the children received cakes and sweets.
In some communities the Chatan Torah and Chatan B’reshit were accompanied home with processions, music and dancing.
Jews were subject to so much oppression and persecution that they relished any and every opportunity to rejoice.
The Chassidim made their contribution to the history of the festival, but they neither invented or created the occasion.
Of course there were places where the festivities were so structured that they were almost as grave as Tishah B’Av, but on the whole, nothing could restrain the people’s joy.