database as persistence bucket

RDBMS are rubbish as persistence stores for OO systems so why is it the norm to use them? It leads to sensible people using them as just a persistence bucket. Using them as the point of integration is seen as being very old fashioned. Maybe due to their age rather than elegance the tools alone make it very attractive.

Data legacy

Nice things like automated testing means coders can relax when it comes to code structure and actual implementation but definitely does not mean we can relax about data legacy. External APIs, even for people, build up a very hard to change legacy. Even more often forgotten is the rubbish that sometimes gets put into customer databases in a hurry to get a new version out.

Seems to me it is worth being very anal and putting a lot of thought into everything that will build up legacy. Public APIs, UIs, datastores...