I have had a similar experience.  I left the coast where we were camping to return to our home last year.  It is about a 2 hour drive of mostly two lane, winding road along with a climb and decent over a small pass.  When I got home and backed my 5er (approximately 20000 lbs) into my shop and got out to unhook, I noticed a bunch of crud on the stabilizer jack behind the door side rear tire.  Upon further inspection, I discovered the crud was brake fluid and accumulated dirt from the drive home.  Somewhere on my route, the brake line sheared off at the caliper on the 5er and I completely lost trailer brakes.  I had no idea I had lost the trailer brakes because my HDT tow vehicle could easily handle the weight of my trailer regardless of whether it had brakes or not.  It was very comforting to know the truck could "handle" the trailer no matter what. 

I used to tow a 15000 lb 5er with a Duramax dually along the same route regularly.  I lost trailer brakes due to a faulty umbilical connection a couple of times and I could definitely tell the trailer had no brakes and it made me pucker a bit with that set up.  I will never go back to towing with anything smaller than my HDT.  It is definitely not about what it can pull, it is about what it can stop (for me anyway).

Ho-hum, here I go, preaching to the choir.

I've lost trailer brakes too many times. (once is too many...)  Broken wire under the trailer, dislodged trailer cord, faulty ground, outright brake controller failure, etc.  While these events are inconvenient when towing with "enough truck", they're probably not dangerous.

My quest for "more truck" started when we were pulling a pop-up with a srw F-250.  The trailer brakes were junk, and going down Wolf Creek Pass I had both feet on the brake pedal.  Wife and kids didn't know until we were stopped.

Certainly not all trailers justify a HDT.  But why tow without a safety margin for when things go wrong?  Too much truck is about right.?

My 3 axle toyhauler has pretty decent brakes as rv’s go. The Maxbrake controller waited till a long CA downgrade, in the dark, to crater. The retarded brake on the little Cummins and 6 speed I shift it in the won ton held pretty good, saving the truck binders for the curves. 
Oh and I have that truck driver (even though I aren’t one) habit of not starting down a grade at Mach chicken...

Thought the air line oh sorry I mean little wire had disconnected - nope - Maxbrake controller finished.

So I bought a Tekonsha jerk a matic the next morning  ...they are quite a thing too when you are used to proportional trailer braking ?