Here's how I responded:
There is no perfect system.
Your point about the undesirability of elevators (security, smells, delay etc.) is a fair one.
But Seattle faces two very big problems -- topography (hills & water) and narrow rights-of-way -- which constrain every possible solution.
Once we decide we want to create a city/region-wide system we need speed -- no meandering trolleys -- and have to either go down below-grade by elevator or up above-grade by elevator. There are no other options.
Oh you could put a system on the street, but then you lose predictability, speed, safety and neighborhoods. You have to dedicate the curb-side surface lane to traffic and you eliminate the possibility of that arterial ever being a pedestrian-oriented street -- you are dedicating it to being an urban arterial.
There is no way out -- it's a trap with no exit -- which optimizes for every variable; you can only satisfice.
The monorail -- while not perfect -- is like democracy, the least bad way.
The sole remaining option is to choose the "no action alternative" -- which is in fact what we are doing -- but not by choice but by dithering indecisive default.