dunninla,
One, you are confusing "liking" a community vs. selecting -- selecting a community, obviously, doesn't necessarily going to mean you like it and it could work both ways -- one who got their first choice or one who got their fourth choice.
Two, with your same logic -- how do we know a Cadet or MIDN (non-prior) will really "like" being in the military?
Whatever the statistic is, it is. Bottom line, if one isn't comfortable being in either service or selection available, then one needs to reconsider why they joined the Naval service. The number one reason should always be selfless service (to country, DON), meaning whatever one gets, though how unfamiliar, they will put forth their best effort and somewhat embrace their selection. Life isn't always fair and in the military it is common to be ordered to do things you wouldn't "like."
Also, there are always stories about how someone got their second or third choice, which they thought they were going to hate, but ended up loving it. My class saw MANY male MIDN get "drafted" (told) for subs...it wasn't what they had envisioned to do....however many of them carried on smartly and are progressing through their pipeline as if it was their first choice. In the Navy (I can't speak exactly for USMC), there are very seldom opportunities to transfer.
If one is concerned they might not get the Service Assignment they like, well then they need to reconsider what they signed up for.