Uhh, well that's why they're branched off then isn't it? And you only need level 50 to get to to the half fall damage perk for Heavy. And why would you even want that unless you were going for the weightless heavy armor perk? If your "monk" is going to be using light armor, then you just need to wear enough heavy to get it to 30 and get Fists of Steel. In any case, Bethesda was obviously gearing "unarmed" characters towards the heavy armor perk tree, probably to increase that build's survivability. If you have a very different build in mind, you'll just have to work with what is there but it's certainly still possible. Just my take some workarounds, but that sounds like real life to me anyway.
I'd want that perk to jump from higher places without taking too much damage.

Taking Fists of Steel with a light-armored character is pointless, because you can either take advantage of Fists of Steel - then you need to wear heavy gauntlets. Or you can take advantage of light armor perks - then you need a full light armor set, including light gauntlets. You can't have both.
And taking less falling damage in heavy armor / dodging better in full armor doesn't sound much like real life to me, by the way.
It just seems to me like what you really wanted was a separate skill for unarmed, which would make more sense to me than carring which skill tree the one unarmed perk fell into. In other words, you complaining that the perk(s) that you want for your monk build are in heavy armor when you want your monk in light armor draws a "too bad, so sad" response from me, but if your initial dissapointment was that unarmed isn't it's own skill (which would probably elminate having to chose between heavy and light armor as either would work), then I can understand.
While that would be ideal, what I actually want are light armor perks that don't try to catch up with heavy armor (meaning, increasing defense), but provide advantages for a unique playstyle.