Here's what could help - turning all users into (exit) relays. That strategy has worked for torrents very well - all downloaders are also seeders (I think it's a similar situation).
This solves multiple things:
1) makes it much harder to do traffic analysis
2) makes it almost impossible to "go after relays". Sure, they'll still try to arrest some here and there, just like they try to arrest people who torrent movies, and even with the mass copyright laws they couldn't stop piracy. There were just many more who did it, making the hunted down but a tiny percentage.
3) should make the legal defense case even stronger than it is now for relays. You can say today that "you don't know what's happening through your relay", however you still have to choose to become a relay. I think that says something. It may not be a huge case in the prosecutor's favor, but it may convince the judge to be against you in some cases. But if everyone is a relay and you can use the defense that "this is just how Tor/Firefox works", I think that would work a little better
4) should improve speed since relays can't be choked anymore
5) I'm not sure about this one, but I think it should make it much harder to DDoS Tor users/hidden services as well?
I think having the way Tor works currently is a design flaw in Tor. Tor should be "fully distributed" in a way.
As for the argument "but then no one will use Tor if they are forced to be relays!" - I just don't buy it. I think there may be some that will get scared in the short term, but then see Tor actually gets more secure this way in the long term, and will return. I also believe Tor will get more new users in the long term this way.
EDIT: What I'm referring to is turning everyone into exit relays/nodes. My arguments remain the same. If it's not illegal for people to have an exit node in US (as Tor claims [1]), then it shouldn't be illegal for millions to do it either. In fact it could be a sort of stronger civil disobedience thing.
Plus, even if it is illegal, so is piracy. That hasn't stopped millions from doing it. Just like "being gay", what's legal and what's illegal is a matter of how we shape our laws. To change those laws, first you need someone to break them and change the society in a different direction. If you didn't have anyone to break a law in a certain direction, then laws would never need to be changed.
[1] - https://www.torproject.org/eff/tor-legal-faq.html.en