An exclamation point [ ! ] at the end of a sentence conveys a strong emotion. In dialogue, it indicates that the speaker is shouting.
Writers of academic prose do not have strong emotions nor do they ever shout.
Exclamation points make your writing sound amateurish, juvenile, and shrill. If you need to convey intensity, use sentence structure and word choice, not exclamation points.
Compare:
Alfred Hitchcock never won an Oscar for best director!
To:
Alfred Hitchcock, one of the greatest directors of all time, never won an Oscar for best director.
The first sentence tries to bully the reader into feeling something. The revision treats the reader with respect by simply presenting information.
In short, never use exclamation points in academic writing.