I don't think it's that simple. For example, currently Google Docs doesn't support merged cells in tables. If they add support for that in Google Docs, it means

I don't think it's that simple. For example, currently Google Docs doesn't support merged cells in tables. If they add support for that in Google Docs, it means they would need to add support for it in all of the exporters as well. So even though the format isn't changing, the subset of the format that Google works with is.