The second reason was that N.W.A had a very short career. They were a supernova that were briefly a major cause celebre; then their most important member left, the remaining group released an EP and second album that didn't live up to the first, then they blew apart in several different directions. The original group with Ice Cube released a single album, while N.W.A in all its guises released two and a half.
Which Hall of Fame member released the least amount of product in his or her career? It's gotta be Ritchie Valens, who put out two studio albums and one live album, none of them released during his lifetime. N.W.A would arguably beat that record, without the excuse of having died at age 17.
But I have been convinced that N.W.A's place in history is worthy of induction. They weren't exactly the first gangsta rappers - Ice-T's Rhyme Pays came out a year before Straight Outta Compton - but they were far and away the most popular and enduring. Compton went triple platinum with virtually no airplay. They also virtually invented West Coast rap; aside from Ice-T, until N.W.A, hip-hop was predominantly a New York phenomenon.
And after N.W.A? They paved the way for Tupac, for Eminem, for Too $hort, for Snoop Dogg, for 50 Cent, for Kendrick Lamar, who just released what the president of the United States called his favorite song of the year. The President of the United States.
That's not to mention the legacy of the members themselves. Ice Cube and Dr. Dre were two of the most important hip-hop figures of the 1990s, and Eazy-E and MC Ren both had solo platinum releases. They would be the Beatles of hip-hop, if the Beatles had broken up after A Hard Day's Night. The only rap group that measures up with N.W.A in influence would be Run-DMC, and they're already in.
Look at it this way: How many musical groups get a biopic made about them? It's not uncommon for solo artist to get their own movie, like the aforementioned Ritchie Valens, but I can't think of any other groups that have done so except for the Beatles, and those were primarily squirrely European art films. (Plus, major props to Ice Cube for having Ice Cube Jr. portray him in the movie, which is awesome.)
I'm also pretty sure they invented that whole "Straight Outta" trope. Was that phrase used anywhere prior to Straight Outta Compton? Not that I can find, but I'm not exactly a lexicographer. Not a professional one, anyway.
So in the end, I've decided that their cultural influence and impact on the world of music for the past two decades is impossible to ignore. I vote YES for N.W.A.