upgraded wyrm has 3 hp. shockwave, lightning, rage elixir, firestorm, fire lance, then drain life and ice bolt only require 10 quanta for enough dmg, 2 turn alfatoxin, 3 turn infection, iridium or basilisk, all shields but wings affect wyrm.
UG does not need to be upgraded, 3 snovas either way is enough quanta. butterfly effect, steal, explosion, reflect and jade shield
it also takes a wyrm 3 turns to do 25 dmg, where it only takes 2 for a ug to do 20. now unless youre playing a deck that produces a lot of air, chances are after you play the wyrm, it might even take up to 4 turns to do that 25 dmg seeing how it costs 2 air to activate.
ug is a better finisher compared to a wyrm - yes
there are less cards to counter or remove ug - yes
ug does more damage over time - no
i think the problem lies in the fact people are not thinking beyond the norm. 1 ug can make a difference in a couple ways, 1- fodder, if you have other more important perms, play the ug to draw out the steal or explosion from enemy
2- finisher, 20 dmg is a lot coming from 1 card
nightmare, plain and simple, if you use it on one of your creatures that the opponent cant play, not only can it dmg them up to 16 dmg, AND heal you for 16 life, they also dont get to draw a card on their next turn (unless they can play something and have another way to draw cards), and it costs 1 dark. this card would do well in lava destroyer deck, most likely giving you more 4 turn wins than without.