Originally Posted by Gleithan

If Blizzard doesn't like downranking, they should just flat-out not allow it and design classes/encounters in such a way as to not make it necessary. As it is, Warriors and Rogues (I think) already can't downrank (since their abilities never go up in cost it is a moot point, but still). So they have the ability for higher ranked spells to completely replace lower ranked spells in the spellbook.

The way the game is now, a non-theorycrafting healer suffers in comparison to one who downranks. Since new ranks of spells automatically replace old ranks on the actionbar, a reasonable person probably thinks "I should use the more powerful one now" and never opens their spellbook again. It isn't as bad as it used to be when Heal was a more useful spell than Greater Heal, but it still is an obscure game mechanic that shouldn't be necessary. Healing (and DPSing) can be made difficult enough without requiring downranking.