As far as unintended consequences of adding Finesse to a weapon...
I was unsatisfied with the Versatile quarterstaff simply being the best Simple weapon, completely obsoleting the club and great club. So I removed Versatile and added Finesse. So d6, Two-Handed, Finesse.
Enter the Bladelock with very high Dexterity and Polearm Master. I have absolutely no problem with his final damage output, and I have problems with the investment needed normally to make a Bladelock work...but, I'm not entirely happy about getting that sort of damage from Dexterity that easily, given it's greater usefulness than Strength.
I'm not changing anything for the purposes of that character, but I'm not sure how I would want to handle it in the future, as my goal was to eliminate one-handed quarterstaff and shield combat, the obsoleting of other weapons, and make the wizard a bit better with their iconic weapon, not turn it into an optimal choice for Dex combatants.