I disagree with your point about the +6 being overkill, I was going to use humans as my race for wacky multiclass options that use more than 2 main stats. Again though, I'm not here to argue my build ideas or optimizations, I just want the old system to be an optional toggle. I appreciate that you're trying to mitigate my dislike of the new system, but I am simply never going to like it, though again I appreciate what it's trying to do and that many others will prefer it. Have your system, but please don't erase mine.
If you are planning a whacky multiclass then medium armor is even better. Medium armor is the best for any character that isn't going over 16 dex and doesn't use heavy armor. Being able to have solid armor with a bit of dex bonus(max +2 from dex) is the best armor option for a character planning to go jack of all trades multiclass.