huge files size when browserifying angular

I am just trying gulp + angular + browserify app and got a huge browserified file, about 2M. While all it does just require angular and a sample controller.

// setup gulp task
gulp.task('browserify', function() {
  gulp.src([util.format('%s/app/main.js', JS_BASE_DIR)])
  .pipe(browserify({
    insertGlobals: true,
    debug: true
  }))
  // Bundle to a single file
  .pipe(concat('bundle.js'))
  // Output it to our dist folder
  .pipe(gulp.dest(util.format('%s/js/', BUILD_BASE_DIR)));
}); 


//in the main.js
(function() {
  'use strict';

  var angular = require('angular');

  var indexCtrl = require('./controllers/indexCtrl');

  var app = angular.module('wohu.app', []);

  app.controller('ctrl', indexCtrl);
})();

angular is installed via

npm install angular

The bundle.js is not minified but it shouldn't be that huge. Wonder what the problem is.