I loved the opening things at MK and even Epcot...but Disneyland has so many people who visit all the time, I don't know that a "rope drop" show would get nearly as much attention. Plus there are only two parks (and only one that most people start the day at), so a pre-show at Disneyland just might get a little old for people who are getting there at opening for 5 days.
It would be nice if they had a little something small though. And super-nice if there was an area to wait in before the gates open, but after your ticket was scanned. (I know some days that's Main Street, but even on some non-MM days, I haven't been let in to Main Street lately...)