That depends upon whether you are updating data only or changing the data structure. The CB has a fair number of data-only errors and/or is missing data, most of which could surely be fixed without any data structure (aka schema) updates.
True, but even regular data updates are not something you want to do on the fly in most cases, and that goes double for the CB.
In most databases, each table contains a whole bunch of records which are basically interchangeable. Say you work at a bank; you might have a table of "transactions," in which each one contains a source account, a destination account, a quantity transferred, whether the transfer was successful, date initiated, date completed, and so forth. Every transaction is fundamentally very similar to every other one and their relationships to other objects in the system (e.g., bank accounts) are well-defined.
In the CB, however, every power, feat, and magic item can reach out into other powers, feats, and magic items and change how they work in a bewildering variety of ways. There are a lot of moving parts and the potential for unforeseen interactions is high. Under such a regime, you want to be real careful tinkering with anything, no matter how trivial a change it may seem. I would be wary of releasing even a simple data tweak without at least a little testing.
Then, too, there's the fact that changing the contents of a database is rarely as simple as changing a value in an Excel sheet. One moment of idiocy can blow up a whole table; ask your local SQL wizard what happens if you forget the WHERE clause when writing an UPDATE statement. (You wouldn't think this would ever actually happen. Trust me. It does.) If somebody did that on production, the whole Character Builder could be down for hours.
As for bug fixes: Deploying code changes is a major hassle. If you did it for every little bug fix, you'd spend 90% of your time preparing for and executing deployments. Unless you've got a showstopper, scheduled releases is the way to go.
