Back in 2e my character was a super tough dwarf. 2 fighters in our group, and mine had 18 CON! At first level, we got max hp, and I definitely had an edge over that flimsy elf with 8 CON (no penalty in 2e), with 14 vs 10 hp.
After 3 more levels though, I had rolled a 2,3 and a 4. The elf? 8,9,8. His hit points? 35. Mine? 31. Of course, the Elf had a better DEX too, so he didn't get hit as much. Lesson learnt: if hit points are rolled, don't bother with CON. Put your high score in STR or DEX. If you then roll crappy hit points, you'll die, and get to start a new character that isn't nerfed for no reason whatsoever, or even exactly contrary to the design choice made by the player. If you have a high CON, you could roll crap and still live, while your other stats would be no better off.
Some people argue: "But in the long run it all evens out!". Well if it does, why bother rolling in the first place? Get your random rolls out of my hit points!