He's a compiler, but so was Art Monk, who didn't have a signature catch.
A couple things.
Monk won the super bowl three times as a prominent weapon.
Monk led the league in receiving yards in 1984.
Monk led the league in receptions in 1980, 1982, 1984, 1985, 1989, and 1991.
Gore never won the super bowl. Gore never won a rushing title.
Gore had 1 season over 1500 yards. Gore played 16 seasons but only 9 -slightly more than half - of his seasons went over even 1000 yards.
Gore has 16000 yards rushing but the final 6 he was well past his prime, generally not putting up good stats anymore or particularly effective, but added 5000 WGAF yards to his total.
His 16000 yards puts him 3rd all time, but if you take his empty 5000 yards from his final 6 seasons he'd be around 11000 and around 24th all time around the likes of warrick dunn and lesean McCoy.
Monk has a legitimate case. Gore does not.
Hall of very good, sure. But his one selling point - 3rd all time rusher - is not legitimate and doesn't hold up under scrutiny. I wouldn't reward a guy for refusing to retire long past his prime and just compiling. There's nothing else you can point to and make a case for him.