Hmm... I have the opposite experience – for example, the cost of just one Arena in terms of wood is quite daunting. The Monastery also requires a lot of resources, and Angels, both building and hiring them, seem to cost more than Dragons. As for the Elves, all you need to do is find enough wood, and by week 2, you'll have a decent army. Plus, if you have 10 stones and 20 crystals after a few days, along with enough gold, you can get Dragons and Unicorns, and they're quite cheap.
This is what I meant by development speed.

The Arena costs 30-35 wood. The High Elves require 20 wood, and if there are no Centaur Stables in the castle at the beginning, it's already 30 wood. The Monastery... 2 of each resource isn't that much.
Green Dragons require 25 wood + 45 stone + 4 sulfur + 4 mercury + 14 gems + 34 crystals. Golden Dragons will cost 30 wood + 80 stone + 10 sulfur + 10 mercury + 20 gems + 54 crystals.
Archers require 15 wood + 15 stone + 20 sulfur + 20 mercury + 20 gems + 20 crystals, and if you add horses, you'll need another 30 wood. It's easy to see that building Archers is less resource-intensive than building Golden Dragons.