Comment 20 for bug 15051

Other popular distributions do have grep -P available - for example: RHEL 4 and SLES 9.
RHEL places PCRE in /lib while SLES appears to link PCRE statically.

I'd argue that Ubuntu, either on the server or desktop, targets systems with enough resources to have libpcre in /lib. If there's room for BDB, Perl and Python, surely there's room for libpcre.
This takes several hundred KiB which, on a modern system, is usually acceptable.