I switched from my domain ( a .co.uk) to gmail for personal email because it makes things clearer to other people. Being @gmail means people know to gchat you or send you a google doc. Or add you to an analytics account. A bunch of third party tools like browser plugins, gmail mail clients also don't work with apps for domains first. That has become less of an issue over time, but there has certainly been a reduced hassle just having a gmail account.