Afaik one of the main problem with the software of his is that it tends to sacrifice ergonomics in the 99% common cases for some obscure theoretical observation.
This is of course about tradeoffs and about the complexities of the problems you're solving, but his software is full of choices that only make sense if you priorize elegant code over elegant software only to then grow into something that is neither.
Lennart worked at Red Hat when he was developing systemd. Red Hat's largest customers often have wacky, weird requirements that you would have never thought of unless you were in that specific customer's situation.
This is of course about tradeoffs and about the complexities of the problems you're solving, but his software is full of choices that only make sense if you priorize elegant code over elegant software only to then grow into something that is neither.