People came to Disney before FP+.. before FP.. a paid express pass isn't going to scare off the masses. They don't get scared off from Universal.
As to the 30 minutes, I think I'm understating it. Earlier in this thread, Len Testa (touringplans) stated that the effect of Early Entry will cause off-site guests to have to wait an additional 1-2 hours in lines over the course of the day (the effect of walking into a park that is already filled with guests). So saving 1-2 hours in line, at every park, every day -- That's a pretty big benefit. Arguably, it's a much better benefit than the only morning EMH... which was just typically once per week at any park. And since it was generally only 1 park per day, that park would just get higher attendance. Now, on-site guests get a half hour, at every park, every single day. That's a 1-3 headliner advantage over regular entry guests. (For example, at Magic Kingdom, one could probably do Mine Train, Peter Pan, and then get in a short line for a third headliner, right before official open. At DHS, do Slinky Dog, TSM, and get in a short line for Falcon before park open)
Early Entry could be rolled out in a less advantageous way, but no matter how they roll it out, it will put offsite guests at a big disadvantage compared to on-site rope droppers.