Enigma encryption still secure?

Everyone knows that the Enigma was cracked during WWII and is no longer considered to be safe, there has even been a movie made about it. But, i think that its a bit more nuanced than this. The Enigma M4 has a key space of over 80 bits, way too much for anyone to try a brute force.

In order for messages to be cracked during WWII a number of different things was needed:

• Message length above 100 letters, statistical letter attacks becomes impossible else.
• Known cribs/words in the text, like "weather" "headquarters"
• Procedural errors from the users, like using the same message key twice

I have a theory, that if used correct, the Enigma M4 could be a secure cipher. In fact there was a couple of messages not decrypted until the 2000s, and according to some sources there are still messages that hasn't been cracked yet, du to being too short or not including any cribs.