Christmas is consequential to the plot in Home Alone though. The family left for Paris because the trip was a Christmas Gift from a relative. The robber's motive for working that neighborhood was they knew a lot of families would be out of town for Christmas. The whole reason the mom couldn't get back to Kevin was because of the travel backlog during the holidays. The plot of Home Alone wouldn't make any sense for any other time of the year. To try and tell it around another time of year would've required a big chunk of the plot to be rewritten. Its not remotely comparable to Die Hard, which literally could've taken place at any other time of the year and its the exact same movie.