>>130185178I hate the whole Whor thing and it was obviously a stunt to garner controversy and mystery. If you want an explanation I guess you can say that technically Thor has "magical" powers that can allow the inheritor of his powers to shape change. Cap didn't need to since he didn't need a new identity.
Basically they were drawing inspiration from the Donald Blake era with Jane, but even then it didn't make sense and was just an excuse to give her a "secret" identity.