For purposes of dramatic tension, the weapons tech gap betwee ninvdters and defenders is often underrated. I can accept that for the sake of Willing Suspension Of Disbelief, and sit back and enjoy the show.
For me, a bigger problem is the motivation of the Invaders.
They all seem to be a collection of genocidal loons. Nearly all of them seem to want to wipe us out. A shining counterexample is the alien government of which Klaatu and Gort are agents in the original Day The Earth Stood Still. They come here to deliver a message: "We don't like the road you are headed down. We will not allow you to become a threat to us. And Klaatu bent over backward to avoid killing anybody while making his point about the relative balance of power.
Which is why I won't watch the remake, the aliens in that movie revert to the genocidal loon standard type.
I'd love to see something different, more complex. My aborted Domino Theory game was to be an exploration of that, Earth is discovered by more than one squabbling interstellar power in quick succession, the aliens get dragged into Cold War politics somewhat against their will, find that they are dancing to the tune as much as calling it, hilarity ensues. (Alien invasion and late 1960's political tension and social upheaval? What could possibly go wrong?)
Or another example, it has been said that Trade Follows The Flag. It might be more accurate to say The Flag Follows Trade. How about a story of competing merchant explorers - whose competition could get literally cutthroat, just read a history of the Spice trade on Earth. And then the alien government types show up. Again, Hilarity ensues.
But this would be harder to write.