Oh no wait, this exact same discussion has happened in almost every major gaming community when a gay character is introduced, and it's never a problem.
The thing about her being gay being "shoved down your throat" is that characters in league can't be in depth in the way that characters in a show can. Almost every character in league can be described with a single adjective. This is done in good and bad ways, off the top of my mind, Evelynn is a example of how this can be done really badly. However, even to that end, the only bits of neeko that demonstrates her sexuality are her lines when she interacts with other female champions. Her being cheery and... bug... y, is the majority of her lines. My only complaint is that she's too similar to zoe in such a short time, but even then it's exclusively aesthetically.
And to those who hate neeko for being gay;
DM For Rat Facts signals that enemies are missing