>>3. PhD programs are often used an immigration tool rather than as preparation for academia. Many PhD students I worked with were getting PhDs so that they could emigrate from India/Pakistan/China to the US and get a well-paying job. I'm sure a similar phenomenon occurs in the UK.
I don't think this is true at all. Why do PhD (4-6yrs+), when a MS is enough to find a job and get an H1-B/GC ??
Well for starters, an MS in the US may cost $40k-$60k/ year for a foreign student (as funding is very hard to get for an MS student), whereas during a PhD you'll get paid about $20-25k/year. Also, many universities do not offer MS programs in more academic fields, or if they do, they do not allocate them many spots in the graduate program compared to PhD students.
This fits my personal experience as well. All of the foreign students I know who did MS's in the US were very wealthy, whereas only some of the foreign students doing PhDs were.
While not enough in of itself, a PhD will greatly increase your chances of getting an O-1. Which is much more attractive than an H-1B. Also, remember that H-1Bs from India and China have to wait for many many years before they can get their GCs. Hardly worth it.
I don't think this is true at all. Why do PhD (4-6yrs+), when a MS is enough to find a job and get an H1-B/GC ??