Perhaps - and yet Beshear and Cooper didn't even make the short list. The campaign runs polls and projections for all potential VP candidates, so that suggests that they didn't see enough of a bump from those options. And, importantly (for Beshear), Kentucky isn't even remotely in play as a swing state. Nor are Ohio, Tennessee, and WV (the most similar surrounding states). Walz, on the other hand, is projected to appeal to voters in Minnesota, Michigan, Wisconsin, and Pennsylvania - all important battleground states.
To clarify, I'm not suggesting that Beshear would be able to flip Kentucky to a blue state in an election. I was suggesting that I could definitely see him appealing to independents and moderates in some key states. I view him as the Democratic version of what Charlie Baker was in Massachusetts. (he was a republican governor who won big in a blue state)
For states like my home state of Ohio, while it may not be a battleground state as much as Michigan and PA, the right ticket put forward could change that and turn it into a close-race state once more.
Ohio was a pretty important state from 2016 and before...as whichever way Ohio voted, tended to be the way the the election ended up going. 2020 was the only exception to that in recent history.
Ohio still has that "mix of north and south" that made it a prized state, as well as that mix of college educated and not.
And many of the blue collar Ohioans are still quite receptive to the policies regarding labor and entitlements put forth by the democrats. It's some of the social policies where the Democratic party has been losing some voters in Ohio.
I have quite a few family here who are union workers (some at the Ford plant here in Northeast Ohio, a teamster, and one that's with the plumbers union. They were long time democratic voters... all but one voted for Trump in 2016 (despite still voting democratic in state and local stuff)
That's where people need to delve into the regional component of politics. An Ohio Democrat is going to be different than a NYC Democrat on a lot of issues. They'll share some overlap on economic policy an maybe a few social issues, but the similarities don't go much further than that.
I know for two of my family members in particular, the Democratic Party's shifts on LGBTQ issues (and the pace at which those shifts were occurring) was the wedge that flipped them. For a few of the others, they were bitter former-Bernie guys who still see it as a slap in the face from when the party backed Hillary instead of him.