I think the ownership comment hits the nail on the head.
When we moved to agile roles and responsibilities got blurred and initially things got missed because no-one was sure who owned it, who was responsible for it and who was supposed to do what.
Then there was failure to recognise that certain specialisms are not just jobs to be assigned but vocations. Being a DBA requires a mindset, being a tester requires a mindset, being a project manager requires a mindset.
Yes we can step beyond our own boundaries and multi-skill but we have to respect that things like testing are very real skills and disciplines and deserve respect.
I do wonder if the idea of a multi-skilled cross functional team has somehow resulted in an implementation of amorphous grey goo rather than best of breed.
If you have ever been privileged to work with a professional tester you will appreciate that they operate on a whole new level. They will ask questions of your product that you would never think to ask. My God it can be embarrassing!
The trick is in establishing and maintaining a good relationship with someone whose role will involve identifying faults in your pride and joy; someone who is going to say "my word you have made an ugly baby" but have the diplomacy not to follow it with "it takes after you"!