please reopen this ticket, the problem is still occurring in 1.8
just tested this in 14w05a, and the problem is still present. Docile mobs only spawn in your immediate spawn chunks, and new ones are never seen again if you venture away from that point.
Noticed this as well. Makes it very hard to transport and trade with villagers.
+1
This is a very important issue to get fixed. It completely breaks a lot of contraptions and farms, so i can't imagine it being an intended feature.