Agreed, Hill Start Assist should be standard, on all US models anyway. There is a stop light near our house with a very steep approach. I can sit at that light with Auto Hold OFF and not roll back at all. Nice little feature. Wish they had that many moons ago when I was learning to drive stick!
Actually got some seat time in a manual WRX recently and it will hold on a hill for like 3 seconds then release. Gives rookie manual drivers a chance to engage gear before rolling. Kinda cool feature too.