At high lvls, Monks and Monk-Types can be nigh untouchable because of AD and a little bit of magic.
We joked that there was a Valhala of sorts where the 7 people who actually hit and crit'd our 14th lvl Monk hung out in the afterlife.
)
The RAW is a good game balance.
Weapon Kata Rules do offer a more "realistic" use of the skill, but we don't use MAC, although I do like parts, here and there.
House Rules:
"You can use one specific weapon and is assumed that it's part of your kata for AD".
HR I'll try for our new game:
"You can use any weapon, but you must use the lesser of the 2 skills for both". This still has a RAW feel, IMHO.
(or maybe lower AD by the OB of the weapon used. That's a harsher penalty to AD)
YGMV