I talked a bit about that here, and here.
Like I said in those, it’s a valid criticism and shouldn’t be dismissed out of hand, and I understand it making the ship too uncomfortable for you. It doesn’t concern me personally because:
1. As Vision, Bettany’s age is more an incident than anything. He was hired to voice JARVIS, and the plan wasn’t that he’d one day play Vision. That just kind of ended up working out, especially since Vision is touched up with CG head-to-toe.
2. While they could have cast Olsen older, Wanda starting off as a young woman is a very consistent–one might say integral–part of her character. I don’t think it would be worth it to go a very different direction with her very first depiction on screen just to make her a bit closer to Bettany’s age, especially since Whedon, Olsen, and Bettany have all said they didn’t know if the romance would end up panning out.
3. The character of Vision doesn’t have a quantifiable age, so there’s no realistically measurable age difference between the characters of Wanda and Vision.
But that’s just the way I see it. I don’t think you should make yourself try to enjoy what makes you uncomfortable, and you’re always free to enjoy some campy Silver & Bronze Age Wanda/Vision from the comics.
Those Celestial Bodies 