dr morbius did nothing wrong.
he didn't know the purpose of the krell planet machine or that he was telepathically connected to it.
the krell planet machine wasn't small or portable. the monster that attacks the c-57d's crew is using at least 10% of the planet machine's power (at least 900 of the planet's almost 10000 nuclear reactors at full capacity). you could study it, might be able to duplicate it on a small scale for passing butter or harming one person with a knife, but a society that visits altair iv, discovers it, understands enough of the system behind it to make one and builds it at anywhere near the same scale is kind of asking for it. it's easy to see how it'd be impossible to turn off the machine on altair iv; nobody would want subconsciously to lose the power they get from it and even one telepathic connection is enough to use its entire energy capacity. harder to see how something less than 1/10000th as powerful could summon the same defense even if someone built it on earth.
dr morbius doesn't want to return to earth, didn't want humans to discover what he's found and wasn't ready to tell anyone about it. he most likely planned for himself and then decades later alta to die alone on altair iv and let a future visit try to learn more, which is sad (and crummy for alta) but in his mind he's protecting humanity.