A drake is not necessary for the happiness of the flock. Some drakes can be an absolute pain and others can be enjoyable for the keeper and the hens. There is no significant nutritional difference between fertile and non fertile eggs.
If i could have started years ago with no drakes and kept it that way, i would have. Don't get me wrong i have some sweet, personable drakes but on the whole the dynamics of entire flock change when you have both sexes and not all positive.
Drakes are not like Roosters, they don't guard the flock or watch over.. a few might but generally that is not their nature.