Why is that? Getting the CMS out of their way is one of the primary reasons they outsourced development (or implementation, or whatever) to someone else (agency, freelancer, whoever).
If what they're using day-in and day-out is in their way or not "simple to use", its hindering (to various degrees) their progress in doing what they want to do.
If I make a website for a musician, they want to probably publish musician / band related stuff and go on making music; if they're having to figure things out or call me every time they log in... I've done a very, very bad job at giving them what they need.
I can't say I've ever had a client comment to me that the system was difficult / non-obvious, especially when using WP (even the first few I pushed that used almost vanilla WP admin).
I wouldn't necessarily take client praise as a testament to being good or bad. When I started out I was pushing WP sites; I usually gauged things by complaints (very similar vibe to when I was working on cars).
I have had very few calls / emails about complaints with the WP admin area, though I do/did generally drop them into a less privileged account with less flashy buttons to break things with, as well as set their dashboard up with some notes about how to accomplish tasks specific to their usage (how to post / edit / delete, how to clear the cache manually if they had to, etc).
I might be in the minority there, and I feel like that contributed a bit to the no-complaints thing... but even a vanilla WP admin area is very usable.
If what they're using day-in and day-out is in their way or not "simple to use", its hindering (to various degrees) their progress in doing what they want to do.
If I make a website for a musician, they want to probably publish musician / band related stuff and go on making music; if they're having to figure things out or call me every time they log in... I've done a very, very bad job at giving them what they need.
I can't say I've ever had a client comment to me that the system was difficult / non-obvious, especially when using WP (even the first few I pushed that used almost vanilla WP admin).