Outlawed probably because there seems no excuse to sell a property but not the land with it as a package as it causes problems. There's the issue of trying to sell it later when you have owned the property a a while and the lease is now shorter, and the problem of the land owner make things ridiculously difficult for you if they wish at the end of the lease, basically holding you to ransom, as you can hardly transport your property elsewhere. A building should automatically come with the land as freehold, there's no justification for keeping what clearly should be part of a package.