[hobs]

It's definitely a thing, eg SQL Server Data Tools has this as a default - Schema Compare and Data Compare, and you can just use declarative approaches to defined your final state and let the tool take care of it.

That being said - if you want to do this the downside is usually that its slow as hell, and the non-migration approaches can cost you downtime.

Generic solutions to specific states often means copying all data somewhere else so you can modify the table and then put it back in a useful fashion - a migration often allows more piecemeal approaches.

Edit: a guy I like wrote a good model/migration set of articles http://dlmconsultants.com/model-vs-mig/