Funny how I survived just fine as a professional PCB layout designer for more than decade without a push'n'shove router.
Many PCB designers I know refuse to use it because they "don't want no stinking software moving my traces for me!"
I think it is a question of efficiency. Having real time DRC just makes things so much faster. Not only is the routing faster but clean up as well. I just completed a design with a high speed memory interface. The push-shove differential router was really nice. Sure you can screw with 200 traces manually to fix DRC errors, but I personally have more better uses of my time.
At this point it is like arguing that coding without an editor that has syntax highlighting or shitting in an outhouse. When I grew up we had one. It is really nice that I have now have toilet and don't have to clean the stall. It's call progress!
I personally don't mind the cloud stuff. If you are "open sourcing" it, you really shouldn't care about "protecting IP".
As far as cloud based storage. I have gotten used to Google docs, MBED and dropbox. It generally means that I have many backups. Amazon AWS is many orders of magnitude more reliable at holding files than any kitchen table computer a Maker will use.
The reality is that 90% really like having pervasive access to files from any machine., It is the 10% that bitch the loudest.
The biggest beef I will have is that of version control. I like to have a project repository with everything in it. (Source, documentation, etc). It is easy to life cycle manage something now with SVN. If Altium's stuff is in the cloud, that may make things a bit more difficult.
All it all, it is hard to complain about "free". I will gladly use it (and pay for some extra features). I just hope they don't neuter too much of the good stuff about Altium.