PIE had a more complex morphology, but correspondingly simpler rules about word order. You'll often hear that all languages are equally complex. This may or may

PIE had a more complex morphology, but correspondingly simpler rules about word order. You'll often hear that all languages are equally complex. This may or may not be true (no one has ever come up with a way to measure the complexity of a language, so the statement is fundamentally meaningless), but it certainly seems true that languages which are more complex in some areas are less so in others. It's possible that languages with smaller groups of speakers tend to be more complex, though, which might apply to PIE.