I don't think Magic and Raft are anywhere close to the importance of Tcl, though I've probably at some point used a chip that was designed in Magic. And, while I like Tk and find it inspiring, the number of Tk apps I can remember ever using (that I didn't write myself) is maybe three, and they weren't very important to me.

As for Sprite-LFS, I really enjoyed the Sprite LFS paper and found it inspiring, but my conclusion was that Seltzer's followup BSD-LFS paper falsified some of its more surprising claims, and ultimately the underlying predictions about the relative trends in RAM size and disk size turned out to be wrong, undercutting the key advantages of the LFS approach overall. Vaguely LFS-like approaches are important to SSDs and SMR disks, but WAFL was already about that LFS-like in 01995 (which is admittedly after Sprite-LFS), and SSD FTLs also do some not-very-LFS-like things. So ultimately I don't think Sprite-LFS turned out to be that important.

Sprite as a whole I'm less able to evaluate. I've never been an OS researcher, but I've spent a fraction of my life reading SOSP and HotOS papers and systems dissertations, and I don't remember seeing anything that came out of Sprite except Sprite-LFS. I was thinking maybe doors in Solaris did, but no, that was Sun's Spring, not Sprite. Other side of the Bay, where Ousterhout took Tcl eventually. So it's possible Sprite was a great achievement, but I haven't noticed it. But I think more likely it's one of those things where we tried the "obvious" thing (SSI across a bunch of workstations) and found out why it was bad, which influenced later efforts like PVM, MOSIX, Beowulf, distcc, MapReduce, Ceph, etc., because Sprite stepped on the mines so they didn't have to. There's a nice retrospective (by Ousterhout, natch) at https://web.archive.org/web/20150225073211/http://www.eecs.b....

So I don't think Tk, Magic, Raft, and Sprite-LFS really have the same level of significance as Tcl. Sprite maybe.

I don't think it's bad to spend a lot of time and effort on things that turn out to not be very significant, for two reasons. One is that, after a long enough time, very little indeed remains very significant. (Who, today, can recount the disappointments of the Minoan queens?) The other is that things you could do that are significant—even for a little while—are usually things that will probably fail. So if you spend a lot of time doing things that might be significant, you'll fail at most of them.

But in Ousterhout's case, one of those things did succeed brilliantly, and it was Tcl.