Survival helps with initiative and elemental resistances, while speed helps with hit rate, recovery time and evasion. If you neglect these, you could find yourself being hit first and more frequently, while taking longer to recover.
I am planning for moderate strength (enough for equipment requirements, plus maybe a buffer in case of disease) and a high agility. So far with constitution I have been leaving it a little low, but still high enough I am not using too many potions. Hopefully some good equipment and vitality charms will mitigate the need for too many constitution stat points. I was trying to keep speed and survival close to my character level number, but with equipment bonuses to reach, they have fallen a bit behind. My DK has trouble with recovering when fighting several strong monsters at a time, so I need to get his speed up, at least.