It does help in that regard.
One of the pain-in-the-butt things about Shapechange/Polymorph is that they encourage the player to dumpster dive through ten books to find the best form.
Another thing is that these spells all key off of monster Hit Dice, which is a notoriously bad metric for measuring power. Challenge Rating, while not perfect, is better. I remember a version Polymorph that K created, and you could assume a creature of max CR equal to your Caster Level - 3. Subtracting three is important because a creature of equal CR to the party is in theory a good challenge for a party of four people. I have know idea how it works out in play. I've never play tested it myself.