We should not be put off with errors, because ukulele, guitar and piano are foremost accompanying instruments, yes. In that they work great.
For melodies they can work sort of as a compromise. Not to be admired too much, but admired in a sense that they can do both. I could never much care about music from pianist Richard Clayderman, was it the name. The entertainment stuff. Some fixed pitch instruments like accordeon work better because of the dynamic volume control of a voice.
Beethoven's piano music is another matter, cause it is so much based on harmony more than melody.
In the hands of a skilled player, the ukulele handles melodies beautifully and is quite admirable, thank you very much.