The framers did not consider the babies of illegals when they framed the 14th amendment because we didn't have immigration law at the time so they could not have wanted to confer automatic citizenship on the babies of people who were unlawfully in the United States.
1. Usually when "Framers" is used in the context of the US Constitution, it refers to the fifty-five delegates who were at the Constitutional Convention in Philadelphia in 1786-7. None of those people were alive when the 14th Amendment was drafted.
2. Also, these Framers, and generally everybody who lived in the early United States were only a few generations removed from people who immigrated from Europe, if they haven't arrived newly themselves. Everybody pretty much gained citizenship by arriving in America on or before it declared independence. (Slaves excluded.) They all were essentially "anchor babies".
3. The people who did draft the 14th Amendment specifically wrote the amendment in the way so that there would be no political considerations concerning who got citizenship -- they were trying to grant all rights of citizenship to the former slaves. That is why they chose birthright citizenship. You can't contest place of birth.