With less people on the planet there won't be as much of a problem with food shortages and possible will reduce the use of greenhouse gases affecting the ozone layer. Also, it may help China's overpopulation problem so it can benefit humanity, unfortunately it would come at taking people's rights away, which is something I cannot possibly abide by.
I know this isn't going a popular comment but this is my opinion. Look at biologically, people with genetic "disabilities" such as partial blindness, cystic fibrosis and haemonphillia, have a high percentage of passing their conditions to their children and they carry it on passing it to the future generation. In nature organisms with genetic disabilities would have died by a young age and would not have reproduced, therefore preventing further spreading of these conditions. However in society due to ethics and advanced health care these people with these conditions have prospered and had children who have the same conditions as their parents, however on average these people aren't helpful to society and usually leech off of the government to survive while passing on their conditions to other people spreading it causing more strain on the health care system as well as the benefits system. People with these sort of conditions should be limited on how many children they can produce or if they can at all. This would save money and cut down on the population. This would also mean that less people would have genetic disabilities that could lower their quality of life.
Limiting reproduction from certain types of people could biologically benefit humanity, but would create extreme controversy and offense. The government has no place in determining who can have children, it is a matter of ethics and morality- which the government isn't exactly the perfect role model in. Creating educational programs would be a much better solution.
Although there are a few evil or deranged individuals who should pererhaps not be allowed to reproduce, for the most part reproduction should not be limited. Such limits could be very dangerous if people of certain religions, races, beliefs, etc. were prevented from reproducing. Society would not benefit from limits on reproduction.
No, limiting who can reproduce will not benefit humanity. Humanity, due to cultural and social norms, already limits/restricts itself. These norms mean that women and men in this country will seek the "American Dream". Thus, the women and men will converge and look for a family life. In my opinion, a limit on reproduction in a "free" society in which all do not identify as cisgender or Christian or wealthy will lead to many protests and be counter productive.