haveged was added 8 years ago to increase entropy (and prevent entropy starvation I assume).
A lot has changed since, most notable:
/dev/randomno longer blocks after CRNG initialization (since v5.6, LWN article)
random: try to actively add entropy rather than passively wait for it(since 5.4, merge commit with more reasoning, LKML discussion)
See also: https://systemd.io/RANDOM_SEEDS/
Note: I'm not a expert on this subject, but from what I understand it should be safe to remove