Hands down, if the MLK-165 are not the smoothest, most natural speaker system, your install needs attention.
They are capable of so much midbass, you can run them without a sub. But the install is key. They are revealing, and like reference monitors.
This is how to install them:
http://forum.sounddomain.com/ubbthreads.php/ubb/showflat/Number/1904111/page/0/fpart/1
We have $600 in vehicle treatments and over 100 hours in install.
The tweeters can be silly smooth, if you install them correctly.
The problems you are having are not the speakers, and any drop in replacements can have the same issues. Share pics of the install, speaker mounting, etc.
You can spend a grand on new speakers, and they won't help Poorly mixed music sound better.
You can buy speakers with more midrange distortion (most do) and maybe that would help your perception.