I think if you want to point fingers, go back to pre-1968 when Indiana and Kentucky were applying for a share of the 1500 new interstate mileage that added to the system at that time. The original proposal for I-63/I-164 was to build a new Ohio River Bridge and to connect to US 41/ Pennyrile Pkwy, fairly close to the current I-69 proposal.
From my understanding, the Feds truncated that more ambitious plan back to a 12-mile spur between I-64 SR 66/Division Street. Indiana originally applied to construct an I-63 from south of the Ohio River north to Brazil, IN, providing a route to Indianapolis, via I-70 the rest of the way. I-164 got its proposed route extended from Division St. to US 41 south of Evansville around 1980.