What would be reasons to or not to use a medium light Walleye rod for Bass finnese? Are there anything about "Walleye" rods that would not be advantageous for Bass fishing?

Rods are rods. They have length, weight, power and action. And are much more versatile than most anglers who are infatuated with "technique-specific" think they are.

"Walleye" rods generally are lighter in power than "bass" rods, but I use one all the time for neds, which are light, like walleye jigs normally are. It's about matching the power to the weight you'll be casting, mostly. Give it a try and you'll probably like it ok unless casting really heavy stuff. If you see deficiencies, you'll know better what to buy to optimize your finesse bass fishing.

Walleye rods tend be be exceptionally fast compared to bass rods since the primary method to target them is vertical jigging. This is because walleye have a subtle bite and a very hard mouth, plus jigging action is best on such a taper. I live within walking distance of the walleye capital, the Detroit River. The rods on the shelves here are exactly as I described. While they can be used for bass, they aren't ideal.

St Croix rods have a lot of walleye'ish rod actions. I personally just use my bass rods for them, works great.

They would work just fine

I have a med Lt that I use for bass and walleye interchangeably in the same outing.