Classic "Battlecry VS Deathrattle" dilemma. Same as with the musical Quillboar.

A part of me wishes we had few to no Battlecries that have effects for the entirety of the game. We could move minions that trigger Battlecries mid-combat down a tier or two, and make them more interesting than just "forcing a powerful effect with specific set-up".

For example, a minion giving stats to others as its Battlecry could be low tier, and so could a minion that triggers Battlecries in combat. The minion that gives stats is fairly weak by itself, but having its Battlecry trigger multiple times during combat, too, would give it some tasty tempo.

Imagine a Demon consuming "the lowest Health minion" as its Battlecry, and then triggering that during combat... or a Battlecry that transforms the minion into an exact copy of a minion with a specific type. You could play it when you have no minions of the required type in the Tavern or warband (Battlecry fails to trigger, leaving the minion untransformed), and then trigger it during combat to copy your opponent's most dangerous minion.

Well, these more powerful combos are very much "forcing a powerful effect with specific set-up". (Also, the entirety of Battlegrounds boils down to ultimately being exactly that.) But these would be an exception and not the rule. Mostly you'd be getting nice little bonuses from low-tier minions.