You wouldn't necessarily only do it when the opponent is tapped out. There is a protection suite that guards against removal that you can fight through some hate.
Pyroclasm isn't good because it kills your own guys.
Obviously, Melira Pod isn't a great matchup. As for Melira herself, there is some removal to deal with her. If your opponent doesn't have Melira turn 2, you're still probably going to win.
Vines stop Splinter Twin because you cast it on the Deceiver Exarch
/ Kiki-Jiki, Mirror Breaker
in response to Splinter Twin
. Vines makes it so any creature can't be targeted by the opponent. Therefore, the Splinter Twin has an illegal target and fizzles.
Livewire Lash is just a touch too slow. Instead of spending that 4 mana to play and equip it, I could just be spending it on creature pumps and killing them.
Predator's Strike isn't terrible. The trample is relevant on the Glistener Elf and Plague Stinger. It's pointless on Blighted Angel. However, two mana for a pump spell is quite a bit for this deck, even when the pump has an added bonus.