Sanitizing Form inputs form quotes (' and ")

why CI maintainers haven't addressed this issue yet?

You mean the conversion of quotes to "? Well, I think that's really a PHP issue. It's PHP that is doing the conversion, and Codeigniter just isn't reversing the conversion. I believe later versions of PHP don't do that anymore. Also, somebody might have actually wanted that conversion to happen, and then they would have complained that Codeigniter reversed the desired conversion.

Because it also doesn't make sense of using set_value() everywhere if I have 100 form input fields.

If you're using form_input(), you have to tell it what to display anyway, so using set_value() isn't much different from using $some_value.

PHP Code:

// #1
form_input($field, $value);

// #2
form_input($field, set_value($field);