กำลังฝึกหัด CodeIgniter ได้ทดสอบตาม code มีข้อสงสัยเกี่ยวกับ Helper ถ้า code ปกติก็ใช้ได้ แล้วเหตุใดต้องใช้ Helper

    <nav class="navbar navbar-default" role="navigation" id="topnavbar">
    <div class="container">
       <div class="navbar-header">
            <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#toggleRes">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="index.php" id="mobile">
                   <img src="public/images/logo.png" class="img-responsive"/>
            </a>
        </div>

        <div class="collapse navbar-collapse" id="toggleRes">
            <ul class="nav navbar-nav navbar-left" id="addBar" >
                <li class="active">
                    <a href="#index"> <i class="fa fa-home"></i> หน้าแรก</a>
                </li>
                <li><a href="#about" >ข้อมูลคณะ</a>
                <li><a href="#department">หลักสูตร</a></li>
                <li><a href="#test">ศึกษาต่อ</a></li>
                <li><a href="#404">วารสาร</a></li>
                <li><a href="#404">คู่มือ/แบบฟอร์ม</a></li>
                <li><a href="#404">สารสนเทศ</a></li>
                <li><a href="#404">แผนผังเว็บไซต์</a></li>
                <li><a href="#404">ติดต่อเรา</a></li>
            </ul>
        <div class="col-sm-3 col-md-3 pull-right" id="search">
        <form class="navbar-form" role="search">
        <div class="input-group">
            <input type="text" class="form-control" placeholder="Search" name="srch-term" id="srch-term">
            <div class="input-group-btn">
                <button class="btn btn-default" type="submit"><i class="glyphicon glyphicon-search"></i></button>
            </div>
        </div>
        </form>
        </div>
        </div>
    </div>
   </nav>

<?php
//ปล. nav_open และ div_open ผมสร้าง Function เองง่ายๆ ไว้ใน html_helper.php 
    echo nav_open('navbar navbar-default','navigation','topnavbar');
    echo div_open('container');
    echo div_open('navbar-header');

        $toggle_button = array(
            'type'          => 'button',
            'class'         => 'navbar-toggle',
            'data-toggle'   => 'collapse',
            'data-target'   => '#toggleRes',
            'content'       => '<span class="sr-only">Toggle navigation</span><span class="icon-bar"></span><span class="icon-bar"></span><span class="icon-bar"></span>'
    );
    echo form_button($toggle_button);

$logo = array(
        'src'   => 'public/frontend/images/logo.png',
        'class' => 'img-responsive',
        'id' => 'desktop'
);
    echo anchor('', img($logo), array('class' => 'navbar-brand','id' => 'mobile'));
    echo div_close();

    echo div_open('collapse navbar-collapse','toggleRes');

    $ul_nav = array(
        '<a href="'.site_url("main/").'" ><i class="fa fa-home"></i> หน้าแรก</a>',
        '<a href="'.site_url("main/about").'" >คณะ</a>',
        '<a href="'.site_url("main/test").'" >หลักสูตร</a>',
        '<a href="'.site_url("main/notfound").'" >ศึกษาต่อ</a>',
        '<a href="'.site_url("main/notfound").'" >วารสาร</a>',
        '<a href="'.site_url("main/notfound").'" >คู่มือ/แบบฟอร์ม</a>',
        '<a href="'.site_url("main/notfound").'" >สารสนเทศ</a>',
        '<a href="'.site_url("main/notfound").'" >แผนผังเว็บไซต์</a>',
        '<a href="'.site_url("main/notfound").'" >ติดต่อเรา</a>',

    );

    $value = array(
        'class' => 'nav navbar-nav navbar-left',
        'id'    => 'addBar;'
    );

    $f_search = array(
        'name'          => 'srch-term',
        'id'            => 'srch-term',
        'placeholder'   => 'ค้นหา',
        'class'         => 'form-control'
    );

    $f_button = array(
        'name'          => 'btn_search',
        'class'         => 'btn btn-default',
        'id'            => 'btn_search',
        'type'          => 'submit',
        'content'       => '<i class="glyphicon glyphicon-search"></i>'
    );
    echo ul($ul_nav, $value);

     echo div_open('col-sm-3 col-md-3 pull-right','search');
     echo form_open('frontend/search', 'class="navbar-form" role="search" method="" accept-charset=""');
     echo div_open('input-group');
            echo form_input($f_search);
            echo div_open('input-group-btn');
                echo form_button($f_button);
            echo div_close();
     echo div_close();
     echo form_close();
     echo div_close();

    echo div_close();
    echo div_close();
    echo nav_close();
?>