Back before 4.01 dropped and changed all our Emblems to Points I sat down with a notebook, pen, Wowhead, and my bank alt and started working out what it would cost me to stock up on heirloom gear.
A lot of it I already had. The entire cloth caster set (shoulder, chest, staff, trinket) and the entire "hunter" set (sword, mace, bow, shoulder, chest, trinket).
So I calculated costs for all the other pieces I didn't have, started prioritizing (when do I think I'm going to level another Plate class, anyway?), making all kinds of crazy value judgments and assumptions...
...and then I stopped. And I realized how stupid I was being.
I have 4 80's. And if I break them down, I can cover any role more than once over.
2 Tanks (Druid, DK)
3 Melee DPS (Druid, DK, Shaman)
3 Ranged DPS (Druid, Shaman, Priest)
3 Healers (Druid, Shaman, Priest)
Granted, San will never be rDPS or Heals. And I don't really plan on using my DK for anything more than picking Herbs from this point forward. But the options are still technically there.
The point is, I'm never, ever going to have to rush to bring another toon up to max level. There is absolutely 0 functional reason for me to ever roll another toon again.
Azeroth has changed. It's shattered and shiny and new. Tons of things to see and do that I didn't before. I want to be able to experience them.
And leveling is already so damn fast. Do I really need to speed it up?
Plus I've found out that when I have 4 (or 6) pieces of gear that I never need to replace...it's kinda boring. Half the fun of leveling is going "ooh! That's an upgrade!"
So I decided that I'm going to keep the pieces I have in the bank (since I did purchase them), but unless some crazy circumstance comes along where I need leveling gear nao!, I'm done with heirlooms.