You certainly don't
have to. In our games the only two house-rules for monks are:
1. Martial Arts damage is one die better. We did this just to encourage them to actually use unarmed strikes instead of monk weapons. It is only an average of +1 damage, so losing it really wouldn't bother me, either.
2. Unarmored Movement - Monks can use their reaction to stand if prone. The classic roll/kick-up (?) when a martial artist is knocked down.
That's it. We played an all monk game until 7th level without adding extra ki or better AC and it was a ton of fun.
YMMV, of course.
Pfft!
Monks are great equally outside of combat as good or better than other martial classes--everyone has their best "thing" of course. Step of the Wind alone is great for exploration challenges. And as I pointed out, Monks have AC relatively (+1/-1) on par with other PCs of the same level other than the plate wearing heavy armor types; but that 1500 gp investment is pretty heavy in most games IME.
Again, YMMV, of course.
My point is there is a lot that
could be done, but I've seen several monks in my own games and others and people having been enjoying them feeling like they can contribute, etc. as well as pretty much any one else.
Once more, YMMV, of course.