The VPN issue and the legality are mostly separate issues. I do not think it is illegal to play online poker in the US. There are some states where it is though and the US facing sites basically ban players from those states.
Here is a bunch of info.
https://www.legaluspokersites.com/
The use of a VPN is pretty simple. I am no computer expert but it basically makes the poker software think that you are playing from a designated location. If you open a site like this:
http://whatismyipaddress.com/
It will show exactly where you are. Once you use a VPN, it will show your IP as located in whatever location you designate. You are basically running all your data through a middle man computer. There are many online to choose from and most are relatively inexpensive.
The main issue is that some sites like Stars have a zero tolerance policy and are also pretty good at detecting when you are playing on a VPN. So it gets to be a pretty serious task to set up an account on someone else's name and out of the country address, use a VPN to log in and play, have them cash you out and not rip you off, and avoid getting your bankroll stolen.
The main US site (Ignition, formerly bovada/bodog) has also been cracking down on the use of VPN. It sounds crazy that someone would VPN back to the US but it happens. I have a nephew that played online and loved it but went to a country that was not allowed part time. He tried to VPN back in to the US and was able to play for a bit but eventually they shut him down. I don't really think it is much of an ethical issue. Like some euro dude comes to Vegas and wants to play online some of the time. If he has a legit account in a country where Stars deals hands I don't really see why it matters.
As far as game quality after black friday, it is pretty complex. The biggest problem I think is the overall contraction of the poker economy. The ease pre black friday with which money could be put on and offline made it incredibly available to the average american who just wanted to sit in their home and play. Even if most of the recs had almost no shot of actually withdrawing, the illusion of it kept them going. The sketchiness of the whole deposit and withdrawal process sort of filtered out the masses and polarized the depositors to people who loved poker so much they had to play everyday/pros who needed to make a living, and true degens who were willing to do whatever they could to get their gambol on. It was not super fun to have to go to Ralph's and send a wire to the Philippines and then miraculously have it show up in your account. I mean, ugh, so I hear.
And throughout all this the games get tougher and the training sites keep pumping content, etc etc.
The withdrawals were so difficult too. The checks would come from overseas and bounce pretty often and the effort that it took to weather this storm was fairly herculean. And then the clouds cleared and the sun came out and straight from heaven came the magical Bitcoin. And that has helped a ton with money movement but done very little to make depositing more appealing to the recs. "So wait, what I have to buy a Bitcoin, wtf is that, and then deposit that, and they will steal my ****. **** that." But the Bitcoin is a thing of beauty and the whole idea that I can send you money to your cell phone from mine in one click with no fees and no middle man to take juice is just awesome. The world is a digital place and this will be one of the biggest changes we see in the next 20 years IMO.
The only thing that remains a mystery to me is why a bitcoin poker site has not started to really take off. it looked like Betcoin would get some legs and we got some decent action going for a bit but it has really started to fizzle out and I don't know why.