Ruby is not as "pure" as Smalltalk. I'm far from an expert, but Ruby  
strikes me as a language made by someone who said, "Wow, Smalltalk is  
cool. So simple. Look, even loops and branches are done with objects. Ew.  
Let's make a Smalltalk where the loops and branches are done the usual  
way. Also, let's drop the image concept."

I think the image concept could be improved on, but as far as making  
traditional loops you add both the complexity and rob yourself of a new  
way of thinking, which is really where Smalltalk excels.

As for the ascendancy of C# and Java over Smalltalk, this was entirely  
commercial (and to a degree, condescending). Someone willing to pour a few  
billion into Smalltalk could easily make it a competitor against those  
langauges. I know Sun dissected Smalltalk pretty thoroughly prior to  
inventing Java, but why not make it look like C++ so as not to threaten  
"the masses"? Same with C# which is, in fact, Delphi in C-style dressing.

They could've used Smalltalk. Hell, they could've used the P-code system.  
But Sun and MS wanted control. For better or worse.

Perhaps more interesting, and the reason I keep coming back to Smalltalk,  
is that what was envisioned for it in the beginning still hasn't been  
reached. Computer languages rise and fall with the ephemeralities of the  
business world, and Smalltalk chugs along....