You are correct that you can catch big bass on regular lures, but your success has probably more to do with the location you fish and your several decades experience fishing trophy bass in your waters. It still doesn't change the fact that swimbaits and other big bass lures( this includes large spinnerbaits, buzzbaits,big crankbaits, big lipless crankbaits, jigs with trailers,etc) tend to attract bigger bass than a small lure. There are exceptions of course, just like the +18 pound Texas state record was caught by a crappie fisherman with a small minnow and other people who catch +15 pounders on very small lures like the woman in this article;
http://www.gameandfishmag.com/fishing/bass/largemouth-bass/10-biggest-largemouth-bass-world-records-ever/
She caught that 15-pound, 12-ounce bass on a little Strobe spinner and that bass is bigger than most bass people will catch in Florida.