i dont really participate in these circle shirks, but this is just plain crazy. C4d doesn't always deliver what i want, but as you've noticed r10 and other old version still work great and do enough stuff, this just goes to show how great it is, that you are still using a piece of software that is nearly 10 years old.
viewport performance has consistently improved from version to version. r15 was a massive jump. R17, while might've lacked "fun" features, had tokes and takes. Those 2 features have easily saved me $700 worth of time and then some. I loved r17!
r18 for example i still haven't really completely covered because, most of the new features are kinda project specific.
so my point is: while for hobbyists is might suck with the price tag, and it would be nice if they had an indie version. For professionals it is always more than worth the price.
re:sidegrades: you can rent to own with cinema4D. and it actually turns out cheaper than buying and then paying MSA. so i don't get what people are complaining about.
No one application can do everything. Other apps may have useful features, but none are as easy for sceen set up and proceduralism as cinema4D. houdinis nodes can do amazing stuff, but the object managers drag and drop and childer and parent thing is just amazing. Try using maya's outliner for organizing a scene with many objects.. god.. its torture.