We were able to just walk on rides over and over again, esp MIB, our favorite after WWHP. BUT we had express passes for staying at RPR, which made it easier. I know you can't just count on walk ons anywhere. The minions and Shrek both had waiting lines for EP, but it went quickly within 5 minutes. However, the regular lines were over an hour. I wouldn't do Universal without EP, even at "slow" times.
I agree that Universal is a different kind of vacation than WDW, but that makes both unique, IMO. I still have love for Disney, but get frustrated with the current situation, IE: overcrowding, broken down and poorly cared for attractions, money grabs for things that were always free before, cutting the times in the parks for regular paying guests for the many paid for events. The list goes on. But there is a nostalgia there that lures us back. It is just getting harder and harder to deal with those things. So, Universal is a breath of fresh air in the park world