it was the equivalent of a "family guy" reference, as opposed to, say, a "venture bros." reference -- the former are lazy, because the reference itself is supposed to be enough to make you laugh or be impressed or whatever. "oh yeah, i remember when that happened that one time!" whereas the latter not only make a reference to something, but do something with that reference (like the show itself is a huge reference to the johnny quest ethos, but references those ideas of adventure and success to talk about the mundanities of life and failure).

the brain eels were just that first kind of reference -- "oh yeah, remember when there were brain eels in that other movie!" um, yes, so? it doesn't DO anything with that, it wasn't necessary to the plot or characterisation, it was just there. there were some successful references in the movie too, like sarek's line about why he married amanda, "because it was the logical thing to do", echoing that line from journey to babel. in the original context it was a joke, a way to bring the family back together after being estranged for so long. in the new film it shows us something about both sarek and spock and the choices that spock makes -- and then it's even better later, when sarek clarifies his answer by saying, "i married your mother because i loved her." he wasn't lying the first time he answered the question, because it was logical to marry someone he loved, but it was too difficult or too inappropriate to say it so baldly to spock when he was a child. so once again, it's used as a way to bring the family back together, but in a totally different circumstance from the first, and one which fits the new universe that has been created and says something about the new characters.

the movie had both kinds of refs but i wish it had had far fewer of the former.