Chemically-Induced Fear of Extraterrestrials
Maybe heightened levels of beer and Emeril Lagasse's Steak Rub in the bloodstream of the masses makes an impending alien invasion seem not only plausible, but entertaining as well. This would explain the popularity of Independence Day and Men in Black, both movies that had huge 4th of July openings...and ginormous budgets. And explosions. And Will Smith. Moving on, then.

Frequent Use of the Term "Buckyball"
A "Buckyball" is some sciencey slang for some certain type of molecular structure. There're tons of these "Buckyballs" in The Andromeda Strain, as they are what infect everyone with the virus. And boy, do these scientists like to about it! On and on about the "Buckyballs"! You see, this kind of word is kryptonite to a drunk person, regardless of whether they can understand what it means or not. "Bucky"? Combined with..."Balls"? Oh, brother. You might as well go around saying, "Pizzamidgets!" over and over again.

English-Speaking Jin, Heterosexual Will, And the Bizarro World Factor
Hey, who doesn't love opposites day? And opposites day on a day that's already a holiday? Forget about it. Daniel Dae Kim mostly speaks Korean on Lost. Eric McCormack was the titular gay on Will & Grace. And both actors are in Andromeda, speaking English and not being gay. Can you imaaaaaaaaaagine? Hell, those two things are worth my insurmountable cable bill alone.

It's a Bad Day to Be Human? Holy Shit! I'm a Human! You Don't Think They Mean Today, Do You?! Fuck! We Better Check This Out.
Never underestimate a great tagline. Especially the kinds that make people think doom may befall them at any time, without warning or reason. "It's a bad day to be human" is one of those taglines. While Critters has Andromeda beat with "They eat so fast, you don't have time to scream", the ambiguity of when that "Bad Day" is coupled with the fact that every organism that can read and understand English just happens to be human is a powerful 1-2 punch for an already anxiety-riddled society.

Apparently the Only Other Things on At the Time Were Denise Richards...It's Complicated and The Bachelorette
Or it might be that. Actually. Wait. Yeah, it was definitely that.