This is not something that's still in the future. This is something that is already happening with some jobs at some places. For example, see: Woman Flunks Fitness Test, Gets Firefighter Job Anyway.
This is sometimes called "positive discrimination". That's quite an oxymoron if there ever was one. It's as insane as saying "positive theft" or "positive rape". Discrimination of people based on their gender, race or other such characteristics is never and will never be "positive".
There are several reasons why hiring quotas are a bad idea. Among others:
Increased incompetenceThe purpose of a company is to be as efficient and proficient as possible. After all, the purpose of a company is to make money, to put it bluntly. This is not always a bad thing: Most of our technological progress has happened because companies have innovated and developed new science, technology and engineering. You wouldn't right now be using the computer you are using if it weren't for the hundreds of companies that have developed the technology over the decades and even centuries. And that's just one example.
To achieve this, companies need to hire the most competent people. The people with the most education, experience and/or talent in the field.
Hiring quotas undermine this. It would stop companies from hiring the most competent people, instead forcing them to hire (and waste money on) less competent people. (And of course it would force companies to hire or reject people based on their gender or skin color, which is rather obnoxious in itself.)
If this becomes widespread, it will have a negative impact in our overall progress.
Companies may get punished for doing nothing wrongOculus VR, the company developing the Oculus Rift, has been criticized for not hiring enough women. Their response is quite clear: They have zero problems in hiring women. It's just that there aren't that many female applicants at all. It's hard to hire women that are not applying for the job in the first place. How do you hire people that do not exist?
Imagine that Oculus VR resided in a place where the government imposes fines for companies that do not comply to hiring quotas. What exactly should the company do in this situation? There are no female applicants, so how should they comply with the quota? Are they just supposed to be paying fines for non-existent applicants, or are they supposed to just hire "ghost" employees that do nothing for the company, but who have to be paid the same as everybody else? What sense would this make?
Can be dangerousAs exemplified with the case cited at the beginning of an incompetent firefighter being hired to fulfill a quota, this may in some cases even be dangerous. It can endanger lives if people's safety and well-being is put into incompetent hands. This quote from the article is rather telling:
Some FDNY members are angry. “We’re being asked to go into a fire with someone who isn’t 100 percent qualified,” the source said. “Our job is a team effort. If there’s a weak link in the chain, either civilians or our members can die.”
It increases prejudiceOne goal for these "hiring quotas" is to fight prejudice. Ironically, hiring quotas increase prejudice instead.
In companies that have normal hiring practices, you can know that anybody in an important position is there because he or she is competent and has done a lot of work to get there. It can be assumed that they know what they are doing and what they are talking about.
However, if hiring quotas are enforced, people will become more prejudiced against employees that may have got the job due to a quota rather than being competent. What they do and what they say may be deemed more dubious and taken less seriously, and there may even become in-company soft discrimination against them, because the other employees may suspect that they got hired via quota.