It really depends on data integrity. If you're dealing with what is essentially unstructured data, then yes VARCHAR(MAX) is the way to go. If you've got a structure, then no, I wouldn't use it the way you're describing. It really mucks with the data integrity.

There is also performance and storage concerns for VARCHAR(MAX) when the data goes beyond what will fit on a page that make is so that you should only use it when you really actually need it, not just because it makes the possibility of later changes easier.