Which Visa categories do not contribute to the US economy

The following categories are most subscribed to, or gets the most number of Green cards on a regular basis:

1. IR5 - Parents of US citizens

2. DV - Diversity Visa

3. IR1 - Spouse of US citizens

4. FX - Spouse of lawful permanent residents (exempt from country quota limitations)

5. F4 - Siblings of US citizens

Let's see if and how these groups of people contribute to the US economy. There are some hard truths that need to be discussed. Twenty first century demands that to be successful, the workforce needs to be technically knowledgeable and skilled.

Start with the easy one, DV. The basic premise is to make America more representative of all countries/cultures, but does that automatically mean that it will help the economy? 

IR5, Parents. Bringing parents may give some peace of mind to new citizens, but are they not a burden to the overall system? Same can be said about F4, Siblings, if they are not technically qualified or skilled enough for the US job market. It doesn't make sense to allow residency for just being a parent or sibling of a citizen without any qualifications.

IR1, Spouse of US citizens. This is one of the most abused visa categories. People who have no other way of getting residency, or who can not afford to wait in the very long wait lists in other categories, typically attempt for this shortcut, and find a suitable citizen partner. Once green card in hand, they are not required to stay committed to the marriage.

And finally FX. Regular applicants of green cards typically include their Spouses and children under various employment and other categories, including F2A. But this FX is a special category for the spouses who are considered "Exempt". Why should some spouses be exempt from numerical limitations when vast majorities are not?

So which groups should ideally get the priorities?

A. IR2 - Children of US citizens

B. F2B - 21+ children on LPR

C. F1 - 21+ children of US citizens

D. E2, E3 - Employment based

Children should stay with their parents, so they should have the permanent resident status. Even if they are above 21 years of age, parents sponsorship helps them to gain education and subsequently employment. Other sources of sponsorship are increasingly hard to get these days. 

Please feel free to provide feedback on the topics discussed above.