I'm A Banana
Potassium-Rich
On the other hand, the restriction doesn't prevent the Mnk1/Sorx. If I wanted to take that Wis bonus to AC, I'm not going to take more than one level of monk anyway!
This is valid...I see nothing wrong with this mechanically. For a few reasons.
1) Wisdom isn't the most desirable ability score for a Sorc. You don't want it bad, but it usually doesn't end up great. If you end up having a good wisdom after putting your REALLY good scores into Cha and Dex (and potentially Con and Int), then lucky you.

2) You're giving up a spellcasting level for that. If you're the party's only spellcaster, then you're REALLY hurting (not to mention that you're a sorc, so you're a bit slow anyway) in the magical artillery area, now. If you're not the party's only spellcaster, then you're still delaying access to the really kewl spells you could use, all for something the equal or lesser of Mage Armor and Shield, not to mention a handy fighter to stand behind. If you want to, go for it, but it seems you're choosing the big shiny empty box over the brown bag with gold inside.

3) There's nothing mechanically preventing a Mnk1/SorX right now. Just take a level of monk to get the goods, and then hop right back to Sorc, and you're golden. You can't take any more of monk, but who needs 'em?

Also, I could see them changing the saving throws to something like d20 Modern's, but because it's a large change, I put it in the "iffy" category.