Possibly because there’s such scant linguistic evidence for the (undoubtedly many) pre-PIE languages in Europe? It’s hard to study something that didn’t leave behind much writing, if any. Basque being a notable exception to that, of course.
With that said, most historical linguists would probably kill for more data on extinct pre-PIE languages.
With that said, most historical linguists would probably kill for more data on extinct pre-PIE languages.