It is VERY clear that the "smoking gun", which frankly was already known, without any doubt now shows that Trump was involved in a quid pro quo, even though his defenders will never likely admit as such. Other witnesses are involved, which is why Taylor's testimony is not a compete surprise, and the last time I heard witnesses can and are often useful in a court of law. [/sarcsm]
And this even stands to even the most basic logic because we know that this administration did not send the monies promised to the Ukrainians until this whole thing "blew up" several weeks ago.
Common sense and other events should tell anyone whom at least tries to be objective that Trump couldn't care less about this whole thing until it was clear that Biden could get the Democratic nomination. So, the answer as to why didn't Trump & Co couldn't care less before this year about the Biden's is really quite clear.