You could also have someone poor who needs to provide for their loved ones (platonic or romantic) as well, in a indirect "I'll die for my family/love" way. That's assuming XCOM isn't officially conscripting everyone and actually pays or provides for their soldiers, even though some members in the recruitment center appear to be conscripted or blackmailed into service.
For instance, you could have someone who never felt "worthy" and keeps taking more and more dangerous jobs/assignments to prove himself, despite the protestations of the lady.
Similarly, you could also have someone (engineers, pilots, ex-military in non-combat roles, civilians with famous parents as soldiers) who is single and insecure and thinks increasing their "manly quotient" will help him in wooing a lady.
There are lots of ways to show a character's motives peeking out through the floorboards. That's kind of how I personally thought of the recruitment post, as a challenge to show off character traits in a suppressed manner so that they could manifest later when the character is actually talking, thinking, acting, and such.