Hi good people,
I play 95% of the time in PVE, so these considerations are related with PVE.
Also i've 8 lvl20 chars (1 of each prof), and have complete prophecies with all of them, and almost there with factions, that being said, i would like to say that i'm not a great great player, but good enough to do most of missions with henchs.
For the people saying that rits output dmg is weak,
Please try this
Communig 16
Spawning P. 12
Channeling (rest)
Rit Lord (weapon of quickening not so good but reasonable until you get rit lord)
Boon of Creation
Flesh of my flesh
and spam
Pain - 2 sec - 21 dmg
Bloodsong -1.75 sec - 21 dmg
Dissonance - 2 sec - 16 dmg and interrupt (each 2 seconds you interrupt an enemy)

Painful Bond - 15 dmg for each spirit attack on foe and nearby foes
You can take also some protection spirit like union or shelter or shadowsong or displacement or ... or you can simple add more dmg output with
Spirit Burn - 5 sec - 56 dmg (you always have spirits around)
How this works: place all your spirits before aggro if possible, and then lure the foes.
Each 2 seconds you will be dealing around:
21 + 21 + 16 (and interrupt) + 15 * 3(minimun if pain bond well placed) = 103 dmg
add 56 dmg, each 5 seconds, if you decide to bring Spirit Burn and
you're doing around 313 dmg in 5 seconds and spending almost no energy.
If you know how to control the henchs you will see how most of the missions are peace of cake.
Channeling line by itself is very weak i agree completly.
Defensive paper:
I agree that a Rit won't replace an healing monk (a good one at least), but as a dmg mitigation a Rit is very good, Restoration, union, shelter, displacement, shadowsong, and ... hey!!! why i'm not taking dmg?
I use to play as an active prot with my monk and as a healer but for protection i agree Rit are very very good.
Try to do Raisu Palace with a good Prot Ritualist and see how easy is this mission.
That's enough for now.
Bye and cya