The name change is fine. You can call them Morning Musume '14, Morning Musume, or Momusu. Whatever your preference is. Besides, Momusu is famous when it comes to changes. Some changes were smooth and some were very abrupt. Despite the changes, Momusu kept on going strong.
Most groups usually have an average life span of 10 years or less. By that time many of the groups are disbanded. Momusu has surpassed that 10 year mark. They are still performing after 17 years and are continuing into the future.
My suggestion for those who are fretting about the name change is accept it; take it as it is. As the Japanese saying goes, "Nan kuru nai sa (What will be will be)." Just continue to support Momusu as they are.