This is pretty much the only good idea I've read in this thread. Instead of making mortar or phase 75+ power we could just remove them from the game. Mine is crap in 1v1 and will always be. And concerning Frost, I don't see the only real problem discussed, which is fmage spam vs nature which makes the latter unplayable. All in all, it's really hard to talk about balance when there is no ranked system where we could see which tactics REALLY lack counterplay, because when i for example see a phase tower spammer in ranked, I will take the free win with fire (or at least make him waste 1 deckslot). Predicting enemy tactics and countering them in advance is a thing I dont see taken into consideration at all in all these balance discussions which kinda make me lose hope on getting to a good result.
It's very obvious that Phase Tower needs a nerf, but rather than removing it from the game I'd rather see some minor buffs for some counterplay possibilites, TOO.
Also one point I want to bring up that isn't taken into consideration a lot is that 2v2 and 1v1 differ quite a lot. For example nature + shadow t1 is absolutely broken, still nobody demands a nerf for SoL or Dryad, because nature t1 is so underwhelming in 1v1 due to shadow and frost matchup. So as you can see, this is a rather fragile and really complex system, where it is very much more likely to make it even worse by just nerfing everything we don't like into the ground. Without an efficient mortar and phase there would only be nox/dryad spam in 2v2.
I think I could go on forever complaining in my mediocre english about the too simplified way of thinking that is propagated by some people here. But let's cut it here and see how the discussion turns out. Sorry if I stepped on too many feet :p
Edit: Last point I want to mention is that Frost and Nature are very map depandent whereas Fire and Shadow don't have this disadvantage. This is probably where we should start tackling this issue.
Edit2 bc I cant help myself: Shadow is also the easiest deck to play which obviously make it seem stronger from noob perspective. Similar thing for fire