I disagree with your assessment of him (though of course I can't disagree with you finding him dull; dull is what I find him when he's doing nothing else but screeching, btw). By the general standards of 'depth' as found in rap music he's done 'deep' songs throughout his career. It's not super intellectual stuff, but that isn't really the point of rap music (to the extent there is one) IMO, it's folk music, it's talking about real life. Danny Brown evokes/d real life, in the poor districts of Detroit, with details I simply don't find to be prevalent in 'uniform generic' underground rap:
FIELDS
'Sitting on porches of abandoned houses
Or sitting in the field on bed bug ridden couches
It's like they all forgot man nobody care about us
That why we all ways end up in prison instead of college
Living in the system working kitchen for chump change
Lost in the streets niggas playing that gun game
Where nobody wins just a bunch of mommas losing
Dead body in the field, nobody heard the shooting
We living in the streets where the options is limited
Cause its burnt building instead of jobs and businesses'
LIE4 (taking on the voice of the typical flexing/stunting rapper and satirising it)
'I'ma blow it all now, mothafuck a later
'bout to cop me a mink; diamond encrusted gators
Car with a TV in it, maid and a butler too
So what nigga this shit rented, right now it's gon' have to do
And I'm gonna take it all with me when I'm gone bitch it's gone too
Who cares when the kids get grown, better figure out what they gone do
Cause right now nigga I got it, nigga what about you?
Broke-ass niggas worth nothing, I can buy y'all in twos
Cause a long time ago nigga, nigga was just like you
Cause we ain’t about the past, it’s about right now my dude
Cause normally I be broke but right now I got cash
Nah, nigga I'm lying, you know that I be fronting'
DRINKS ON ME (from 'The Hybrid')
Say my auntie sort of like an alcoholic
Been drinking since the teens, shitting blood in the toilet
Started real young, nigga pushed the bottle on her
Drunk, fully clothed in tubs, I cut showers on her
But I still love her and I live life for her
She ask me for a dollar, I'm gon' give it to her
Stay drinking on the brew, keep a can in her hand
Tied grocery bag full of keystone cans
Alcoholism has poisoned our city
Liquor store on every corner ain't like that in other cities
So you have a drink, take a hit and pass that
Give a buck to a wino help him buy crack
Dwell on the past, looking towards tomorrow
Wish I could lend my pain, let you borrow my sorrow
Live where lil' niggas wanna be Chris Partlow
Say fuck the lotto, buck's on a bottle, drinks on me
TORTURE (from 'Old')
I feel like a prisoner of war
Reacting sporadically to what the mind absorb
Probably need a shrink, can't get a wink
So I smoke a lot of kush and pop a Xanax to sleep
Close my eyes, look up, fiend said 1 for 8
Can tell that I scared him by the look on my face
Reached in my pocket served him nervous as a surgeon
Can't believe where I'm at, 'posed be writing verses
Heard a knock at the door, 'nother fiend wanted fo'
Gave him what he came for, told him go to the sto'
Let me get a box a box of Swishers, Faygo Cola
Gave his ass another stone now guess what it's over
He ain't come back, before I could look back
I heard the wood on the door crack, and they yelling "Police!"
With this work up in my jeans, man this a bad dream, and it's torture
I wrote more extensively about this in this blog post