Why should I send nudes to my boyfriend and why is he pressuring me to do so?

There’s only one line of reasoning for sending nudes to your boyfriend: because YOU are proud of YOUR body, because YOU want to, and because ALL INVOLVED PARTIES are trustworthy enough to keep that information private by default.  Full stop; no addenda necessary.*

You don’t send nudes to your boyfriend …

1. Simply because he wants them and he’s pressuring you to do something you’re uncomfortable with.
2. To try to get something else out of him (love, respect, money, time, attention, etc.).
3. To bolster your self-esteem through the eyes of another.
4. To incite jealousy, anger, or resentment.
5. To blackmail the other party to do the same for nefarious purposes (making fun of him to your “friends” behind his back; him making fun of you to your “friends” behind his back; to threaten exposure in order to get money, sex, etc.)
6. If you’re unsure he’s going to share them with others without your permission.

Since surreptitious photography and video recording can take place so easily and nearly imperceptibly nowadays, I would just institute a “no nudes” rule with anyone unless you’re getting decent financial compensation. It’s your call, however.

If you have a high degree of trust with your partner and you’re positive he won’t violate your consent and privacy by sharing your nudes with others without your permission, insist he drop trow, take snaps of his own butt naked glory and send them to you as well. Nudity is as nudity does.

* Addendum:  Since you indicated your boyfriend is pressuring you to do this, dump him, do it with a better, consent-respecting boyfriend (if and only if you truly want to), and insist he send you naked pictures of himself (if and only if he truly wants to).  Also, if you do this, make sure everyone’s at least a legal adult. If you’re minors, don’t do this at all: potential child pornography charges could follow if the photos/videos ever got out.