Fundamentally, I think if you're talking about Smalltalk, you're either talking about it in situ, or as it is today, or as an influencer. In the original context, it was thrilling, far ahead of its time in many ways, and lost out because of the reasons you mention: expensive machines, expensive licensing, performance.
If you're talking about it as it is today, it's a mixture of great and horrible and if someone is uniformly positive about it that tells me they have limited experience—either with Smalltalk itself or with competing modern systems.
As an influencer, there are things that can make a reasonable claim to inherit concepts from Smalltalk, especially Ruby. But the influence is not as wide as gets claimed by its proponents. Some of the ideas in Smalltalk are synergistic and don't work well taken piecemeal. Many of the claims about Smalltalk's influence above are unreasonable, either because they are a semantic ball-and-cup game or because they claim a kind of invisible human influence that bears no technical resemblance.
Smalltalk is worth using today, but it has actual faults that shouldn't be whitewashed, and I find the cult of Smalltalk distasteful because it prioritizes in-group mythbuilding over the truth. We should all download Pharo and use it for a few weeks. That direct, personal experimentation is the ultimate cure to technology triumphalism, whether we're talking about Smalltalk or anything else.
I certainly agree with you that we can do better than what we have today, and that Smalltalk has lessons for how to do that which would absolutely apply.