Yes, I agree. But at the time, it solved a lot of problems.
Actually, it completely threw off research in human evolution. It created a lot of problems - I don't think it explained any.
The reaction to the finds was mixed. On the whole the British paleontologists were enthusiastic; the French and American paleontologists tended to be skeptical, some objected quite vociferously. The objectors held that the jawbone and the skull were obviously from two different animals and that their discovery together was simply an accident of placement. In the period 1912-1917 there was a great deal of skepticism.
During the next two decades there were a number of finds of ancient hominids and near hominids, e.g. Dart's discovery of Australopithecus, the Peking man discoveries, and other Homo erectus and australopithecine finds. Piltdown man did not fit in with the new discoveries.
In the period 1930-1950 Piltdown man was increasingly marginalized and by 1950 was, by and large, simply ignored. It was carried in the books as a fossil hominid. From time to time it was puzzled over and then dismissed again. The American Museum of Natural History quietly classified it as a mixture of ape and man fossils. Over the years it had become an anomaly; some prominent authors did not even bother to list it. In Bones of Contention Roger Lewin quotes Sherwood Washburn as saying,
"I remember writing a paper on human evolution in 1944, and I simply left Piltdown out. You could make sense of human evolution if you didn't try to put Piltdown into it."
Finally, in 1953, the roof fell in. Piltdown man was not an ancestor; it was not a case of erroneous interpretation; it was a case of outright deliberate fraud.