"Men are children."
Hello there,such a nice and right into heart question! -Dır is a must to use if you talk about a general statement about a fact.For that reason you shouldn't omit -dır.Examine the following examples:
Güneş sıcaktır.(the sun is hot)(fact) Dikkat et!Hava soğuk.(Be careful!It's cold) In the second sentence we do not need to put -dır,because it is not a scientific truth,it is just an opinion,it would be proved wrong.The weather is cold,accordiong to the speaker's feelings,perception etc. Hope this helps!Best regards!