Wis based characters also have a pretty low Wisdom requirement too (on top of low feat requirements). It gives you a bigger prepared spell variety more-so than outright attack power, due to many useful spells not being damaging.
You can get by with 13Wis quite handily on druids and clerics if you want to, making +1-2Wis either way better or way worse, depending on how you look at it. More is better, of course, but it can almost be considered a dump stat in some builds.
5% Kor rerolls aren't amazing, but it does save from whiffing in vital situations, especially with advantage creating or +d4 spells going for you. I'm probably more favourable to the free skills than the reroll-1's, although it's actually quite good as a built in, always-on ability. But athletics and acrobatics usually come into play regularly enough that having them allows for some weird skill builds with almost any class, regardless of training opportunities (or lack thereof).
For the monk question, sure, why not? Free Wis is free armour, which is always nice. AniMonk (monk or druid heavy) is always a good thing, especially with +2Wis and higher carrying capacity. Why be a bear, when you can be a big punchy bear?
Disguise Self "should" kind-of carry over if precast too. I'm wondering how far you could take the "same basic arrangement of limbs" factor in a WS form. Can you look like a human while in WS bear-form? Apes definitely have the same basic arrangement of limbs as a humanoid, but does a bear/dog/crocodile/horse? At least you can look like a nine foot tall monk when you want to, one that's only medium sized. But can you be an itty-bitty Shetland warhorse, or a cute little face savaging "teddy" bear? When or what from does the spell effect kick in? Can you say "Three foot shorter, that is all" to make smaller looking wildshapes, or would you look like a short Firbolg/humanoid that's actually a bear in disguise when you WS (which is probably far more useful)? I'm pretty sure you'd look like a Firbolg/whatever-humanoid-you-chose (illusion is set at time of casting), but would WS fizzle the spell if the "same basic arrangement of limbs" clause wasn't met any longer? Is four limbs and one head enough, or are hands and feet different, and do front hooves/claws/paws count as feet, or can they be hands? Bears *can* walk on two legs a bit naturally, but crocodiles, dogs and horses aren't renowned for it without extensive training, even if their front and back "legs" are quite different in form and use from each other, as different as our human "arms" and "legs" are.
Bipedal vs quadrupedal, or four limbs = ok? And are bears at least occasionally bipedal?
Another weird side effect from Firbolgs and moon druid WS: everything you carry can be merged into your form (but not necessarily used). You've got large and bigger forms, and a +1 size modifier. Guess who's carrying the Paladin's horse into the meeting, all secret like? Or you can do Ultima 6 Dupre duty, where you carry the boat/skiff for the party at all times, on the off-chance you want to go fishing at some point. I have no idea where "equipment" and "things carried" stop being one another from a player's perspective. There's plenty of stuff you carry in most games, that is equipment, that don't have anything to do with "magical item slots" or anything like that. It's just stuff you carry, in case you need it, thus equipment, thus merge-able into WS. Could you merge a familiar that normally sits in your top pocket? Because if the answer is yes, you can damn well merge in a pally's gee-gee too. And if it's a "living stuff=no, objects=yes" thing, it's still good. Probably not as exploitable, but still good. It might be druidic bears all the way down otherwise.....
There's little to no limit to the random and huge shit you can merge into a WS form either, so you may be carrying a small siege engine or supply cart for all they know, which are "equipment", as long as you could lift it in the first place. Which you often can with +1Str and a size modifier, after a few tries. At worst, WS into something big and strong, lift it, WS into the same form again and merge it. All your stowage problems are now sorted....
Item pinatas are funnier when they hit you for the last of your WS HP and an entire alchemist's lab pops out.