I tend to think that the aikido demonstrations and the aikido video clips posted on the internet are having the opposite affect to that intended. They need to be more realistic with committed realistic attacks with uke resisting and not just falling over so easily or jumping. People just don't think these demonstrations and video clip performances are plausible, and that leads to them thinking aikido is not plausible. If there were more realistic video clips available or demonstrations done which show how effective aikido can be against an unco-operative committed attacker, then there may be greater interest in aikido. Note that I fully understand that in training uke needs to be co-operative otherwise he/she will get injured.
Your last sentence kind of makes the rest of your paragraph impossible, doesn't it? "Realistic" = attacker gets seriously injured. Act otherwise and to the untrained eye, it's going to look like it's not "realistic", like they''re "just falling over" or "jumping". There's no getting around that, so why try? Do you think having the attacker scowl and grimace and bellow is going to make it more convincing? Why not have them throw a few gang signs while you're at it?