I would note that Perl does ship with support for simple hash-based databases through the DB module. The reason as to why Perl doesn't incorporate DBI and DBI-based module support within the core distribution, is most likely due to the wide variety of databases, access methods and libraries which are available for various databases - Which databases should be supported in the core? MySQL? mSQL? PostgreSQL? Oracle? SQLite? Sybase? What version of libraries for each database? Do we include pure-perl versions as well as XS versions?
There are many people who would argue that the core distribution is already bloated - The addition of support for the many databases and libraries available would only grow the distribution further.
in reply to Why Perl does not support database access through core modules?
perl -le "print unpack'N', pack'B32', '00000000000000000000001010110000'"