Fedora 17 : LCD screen backlight brightness on Acer Aspire 5742 issue

[gescape@aspire ~]$ su -
Password:
[root@aspire ~]# cd /boot/grub2
[root@aspire grub2]# cp grub.cfg grub.cfg.orig

[root@aspire grub2]# vim grub.cfg

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Fedora (3.3.7-1.fc17.x86_64)' --class fedora --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-6346facb-6d7b-43d4-a62f-b8b96076e51a' {
        load_video
        set gfxpayload=keep
        insmod gzio
        insmod part_msdos
        insmod ext2
        set root='hd0,msdos3'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos3 --hint-efi=hd0,msdos3 --hint-baremetal=ahci0,msdos3 --hint='hd0,msdos3'  5029942c-6c69-4976-b243-d91ef1eb9068
        else
          search --no-floppy --fs-uuid --set=root 5029942c-6c69-4976-b243-d91ef1eb9068
        fi
        echo 'Loading Fedora (3.3.7-1.fc17.x86_64)'
        linux   /vmlinuz-3.3.7-1.fc17.x86_64 root=/dev/mapper/vg_aspire-lv_root ro rd.lvm.lv=vg_aspire/lv_swap rd.md=0 rd.dm=0 rd.luks.uuid=luks-5dbe04ae-e4be-4eca-848b-bba399c312df  KEYTABLE=uk rd.lvm.lv=vg_aspire/lv_root SYSFONT=latarcyrheb-sun16 LANG=en_US.UTF-8 rhgb quiet acpi_backlight=vendor
        echo 'Loading initial ramdisk ...'
        initrd /initramfs-3.3.7-1.fc17.x86_64.img

[root@aspire grub2]# reboot 

P.S.

I still do not understand why Fedora developers cannot make brightness working out of the box. Options are there under System Settings > Brightness and Lock, but they are simply not working and all you need is just to add one option in a grub.cfg, at least in a case of my Acer.