if i was them i'd put a restriction on the maximum size of a single mail.
exactly. If this restriction is small enough, say 1mb, who's going to have 1000 emails in a webmail account? not enough to make it awkward for google.
Oh, and AFAIK it's not the google april fool, this is. This was announced on the 31st, and has been in too many major news sources to be fake. If it was, they'd lose out big time.