the windshield being dirty, damaged, or flawed makes landing into sun even harder
if you had a perfect windshield you would have the sun to contend with and you could sort of deal with it, but a dirty windshield really makes the situation worse, all the crazing distorts your view.
now imagine looking into the sun for a five hour transcontinental flight, suddenly descending into semi dusk right on the ILS, clear to land and BAM you hit another plane that is on the runway.
your eyes have to adapt from sun to dusk and you trusted ATC
it all happened at LAX