"for" is a complementizer. It signals the subject of the
non-finite clause. "to" goes with "for". As infinitive
marker it signals the predicate of the non-finite clause. The
"for ... to ..." pattern is common after "it is/was/... (not)" +
adjective.
It is important for you to study hard. (you study hard >
for you
to study hard)
It was not possible for John to get tickets for the concert. (John gets tickets for the concert >
for John
to get tickets for the concert)
It is normal for there to be some residue on the machinery. (There is some residue on the machinery >
for there
to be some residue on the machinery)
It is important for there to be two guards on duty. (There are two guards on duty >
for there
to be two guards on duty)
The "for" is required in these constructions.
CJ