Pilbeam's quote was in the context of what Leakey called the "fossil void", and this fossil void was characterized by Pilbeam as "meagre".
But which void was being discussed? I think I asked this before. You have the wrong "void".
Milton offered this quote as evidence supporting his claim that there is not nearly enough fossil void evidence in existence to justify the victory claim of neo-Darwinism. Even member Darwinsterrer admitted the amount of evidence (transitional type/fossil void) by volume today is extremely low.
I would agree that "low" is a good characterisation.
However, some 100's of pieces (some excellent --e.g., Lucy) some much less so ( e.g., individual teeth) fit into a dated framework. Each marks a place and only one picture fits over this partial jigsaw puzzle. At this time there is only one conclusion you can draw and there is enough to draw that conclusion and wait for more data.
Remember, that this particular transitional pattern is only one of many. This type of pattern is painted over and over. So far the conclusion holds. You may take it as being a more tentative conclusion, others a safer one. But there isn't another one available based on the science.
After steping back and looking at the bigger picture of homonid transition, then stepping back again and looking at others you can look at it through the 'eyes' of the molecular genetisist. Again the pattern holds.
When all this is put together, the "meagre" homonid fossils become only part of the jigsaw and the picture becomes apparent. There is more than enough evidence for the bigger picture.
The details, ah, the details, we want so many more full specimens spaced about 100,000 years apart. I wonder if there are there and how long it will take to find them. Unfortunately there may be times when the important transitions were happening in environments that were not conducive to good fossilization.