I think the reason that a bunch of changes don't get talked about is that the upgrade from 7.1 to 8 includes some cool changes, but very few really useful ones.
XControls are very cool, but are useful for a slim minority of users (I really WANT to use them, and I haven't come up with an instance yet where they really made sense).
The scrollbar for arrays is cool, but as previously stated, there was a workaround. I also agree that it's not an optimal UI element. However, this is probably tied for 2nd as the most utilitarian change in 8 (#1 might be the graph palette changes).
Haven't yet seen the utility in afterprobes yet. I might just be running slow, however. It seems to me that unless you customarily keep that option on (which, as you said, slows execution significantly), it isn't very useful. By the time I know I need probes, I probably know where I want them and might as well put the probes in and use them the old fashioned way.
Again, fail to see how matrices are more useful than equivalent arrays. They look cool, and it's probably a little easier to work with. Maybe. But does it really offer any additional utility? And how do they compare in terms of performance?
I think enough has been said about the changes to the File I/O stuff. Suffice it to say, I'm not a big fan of the new setup either.
Variant performance gains are always good. I don't really see that as an addition to tout, however. Almost every iteration of the language has performance increases, I kind of take that for granted.
On the down side, when I upgraded, I found it acutely painful to develop in 8 due to the random palette reorganization. I don't think I exaggerate when I say it probably cost me a couple of weeks of work time (i.e. for the first month, it took me twice as long to program things as it should), until I finally got irritated and manually re-wrote the entire palette set (which brings up an entirely new set of problems, since the editor seems to have gotten flakier and I still can't find the option to save multiple palettes on the same machine).
As much as I like new features, I resisted upgrading to LV8 for a good long while because it didn't offer anything I needed. Once I did upgrade, my hesitance was shown to be warranted, as the new 'features' tended to slow me down more than making things more efficient. When I upgrade, I expect that development will get faster, not slower, and that the new features will fill needs that I have (i.e. multithreading, undo, synchronization VIs in LV5; waveforms, control refs, variants, polymorphics in 6; events in 7). I cannot say that going from 7.1 to 8 satisfied that expectation.