Because for an employer to sponser an h1b immigrant, they need to be paid more than the prevailing wage for their job in the area, which is a combination of salary, benefits, and other factors.
And how is it ruining higher education? Isn't the point to have a better educated workforce?
If a public school accepts so many international students for their CS Masters program, isn't that a problem with the state school, not the immigration system?
So, US citizens can definitely afford a masters or doctorate - but they are in so much debt from undergrad that they prefer to work than study further.
Among many changes, one of them should basically be a fast track to citizenship for H1-B holders, and not have it be tied to the employer. If they are that smart and that needed we should make it easier for them to stay.
The fact is the H1-B visa program is completely abused in order to bring in cheaper employees at the expense of the rest of the community. These H1-B employees have little recourse, limited career potential and supress wages. The uncertainty of their immigration status means they don't buy houses, start families, or participate in the community. The benefits economists suggest don't materialize.
Futher, the H1-B program has a negative effect on higher education. The H1-B program allows employers to avoid the H1-B dependent designation if they hire immigrants that possess a masters or higher degree from a US education institution. It is a well known backdoor into the US and drives up the cost of education and pushes the citizens of the US out of the classroom. The employers list a masters degree as a requisite which the citizen doesn't have because they couldn't afford it. Take a look at the UT Dallas enrollment numbers [0]. Nearly 90% of the CS masters students are international, and of the entire engineering school 84% of them are international.
It's a mess and it needs to be fixed.
[0] http://ecs.utdallas.edu/academics/assessment-docs/2013/2013F...