Learning to read New Testament Greek isn't a hotdog eating contest.
Sadly, you will find beginning grammars that are anywhere from 500 to 600 pages in length. Beginners need to learn what is essential, not everything an author wants to say about the language. Simple is not necessarily simplistic. Simple means "straightforward," as in a "simple solution." Simplistic means making something complicated seem simple by ignoring important parts of it. I prefer the word concise. A concise book is short and gets right to the point. "Concise" comes from a Latin word meaning "to cut down."
My (simple) message is this: Don't overwhelm beginners with information. Make things easy to understand, use relevant examples, and don't waste their time.